; Test the static branch probability heuristics for no-return functions. ; RUN: opt < %s -analyze -branch-prob -enable-new-pm=0 | FileCheck %s ; RUN: opt < %s -passes='print' --disable-output 2>&1 | FileCheck %s declare void @g1() declare void @g2() declare void @g3() declare void @g4() declare i32 @g5() define void @test1(i32 %a, i32 %b) { entry: br label %do.body ; CHECK: edge entry -> do.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body: %i.0 = phi i32 [ 0, %entry ], [ %inc3, %do.end ] call void @g1() br label %do.body1 ; CHECK: edge do.body -> do.body1 probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body1: %j.0 = phi i32 [ 0, %do.body ], [ %inc, %do.body1 ] call void @g2() %inc = add nsw i32 %j.0, 1 %cmp = icmp slt i32 %inc, %b br i1 %cmp, label %do.body1, label %do.end ; CHECK: edge do.body1 -> do.body1 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.body1 -> do.end probability is 0x04000000 / 0x80000000 = 3.12% do.end: call void @g3() %inc3 = add nsw i32 %i.0, 1 %cmp4 = icmp slt i32 %inc3, %a br i1 %cmp4, label %do.body, label %do.end5 ; CHECK: edge do.end -> do.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.end -> do.end5 probability is 0x04000000 / 0x80000000 = 3.12% do.end5: call void @g4() ret void } define void @test2(i32 %a, i32 %b) { entry: %cmp9 = icmp sgt i32 %a, 0 br i1 %cmp9, label %for.body.lr.ph, label %for.end6 ; CHECK: edge entry -> for.body.lr.ph probability is 0x50000000 / 0x80000000 = 62.50% ; CHECK: edge entry -> for.end6 probability is 0x30000000 / 0x80000000 = 37.50% for.body.lr.ph: %cmp27 = icmp sgt i32 %b, 0 br label %for.body ; CHECK: edge for.body.lr.ph -> for.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.body: %i.010 = phi i32 [ 0, %for.body.lr.ph ], [ %inc5, %for.end ] call void @g1() br i1 %cmp27, label %for.body3, label %for.end ; CHECK: edge for.body -> for.body3 probability is 0x50000000 / 0x80000000 = 62.50% ; CHECK: edge for.body -> for.end probability is 0x30000000 / 0x80000000 = 37.50% for.body3: %j.08 = phi i32 [ %inc, %for.body3 ], [ 0, %for.body ] call void @g2() %inc = add nsw i32 %j.08, 1 %exitcond = icmp eq i32 %inc, %b br i1 %exitcond, label %for.end, label %for.body3 ; CHECK: edge for.body3 -> for.end probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge for.body3 -> for.body3 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] for.end: call void @g3() %inc5 = add nsw i32 %i.010, 1 %exitcond11 = icmp eq i32 %inc5, %a br i1 %exitcond11, label %for.end6, label %for.body ; CHECK: edge for.end -> for.end6 probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge for.end -> for.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] for.end6: call void @g4() ret void } define void @test3(i32 %a, i32 %b, i32* %c) { entry: br label %do.body ; CHECK: edge entry -> do.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body: %i.0 = phi i32 [ 0, %entry ], [ %inc4, %if.end ] call void @g1() %0 = load i32, i32* %c, align 4 %cmp = icmp slt i32 %0, 42 br i1 %cmp, label %do.body1, label %if.end ; CHECK: edge do.body -> do.body1 probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge do.body -> if.end probability is 0x40000000 / 0x80000000 = 50.00% do.body1: %j.0 = phi i32 [ %inc, %do.body1 ], [ 0, %do.body ] call void @g2() %inc = add nsw i32 %j.0, 1 %cmp2 = icmp slt i32 %inc, %b br i1 %cmp2, label %do.body1, label %if.end ; CHECK: edge do.body1 -> do.body1 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.body1 -> if.end probability is 0x04000000 / 0x80000000 = 3.12% if.end: call void @g3() %inc4 = add nsw i32 %i.0, 1 %cmp5 = icmp slt i32 %inc4, %a br i1 %cmp5, label %do.body, label %do.end6 ; CHECK: edge if.end -> do.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge if.end -> do.end6 probability is 0x04000000 / 0x80000000 = 3.12% do.end6: call void @g4() ret void } define void @test4(i32 %a, i32 %b, i32* %c) { entry: br label %do.body ; CHECK: edge entry -> do.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body: %i.0 = phi i32 [ 0, %entry ], [ %inc4, %do.end ] call void @g1() %0 = load i32, i32* %c, align 4 %cmp = icmp slt i32 %0, 42 br i1 %cmp, label %return, label %do.body1 ; CHECK: edge do.body -> return probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge do.body -> do.body1 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] do.body1: %j.0 = phi i32 [ %inc, %do.body1 ], [ 0, %do.body ] call void @g2() %inc = add nsw i32 %j.0, 1 %cmp2 = icmp slt i32 %inc, %b br i1 %cmp2, label %do.body1, label %do.end ; CHECK: edge do.body1 -> do.body1 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.body1 -> do.end probability is 0x04000000 / 0x80000000 = 3.12% do.end: call void @g3() %inc4 = add nsw i32 %i.0, 1 %cmp5 = icmp slt i32 %inc4, %a br i1 %cmp5, label %do.body, label %do.end6 ; CHECK: edge do.end -> do.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.end -> do.end6 probability is 0x04000000 / 0x80000000 = 3.12% do.end6: call void @g4() br label %return ; CHECK: edge do.end6 -> return probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] return: ret void } define void @test5(i32 %a, i32 %b, i32* %c) { entry: br label %do.body ; CHECK: edge entry -> do.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body: %i.0 = phi i32 [ 0, %entry ], [ %inc4, %do.end ] call void @g1() br label %do.body1 ; CHECK: edge do.body -> do.body1 probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body1: %j.0 = phi i32 [ 0, %do.body ], [ %inc, %if.end ] %0 = load i32, i32* %c, align 4 %cmp = icmp slt i32 %0, 42 br i1 %cmp, label %return, label %if.end ; CHECK: edge do.body1 -> return probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge do.body1 -> if.end probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] if.end: call void @g2() %inc = add nsw i32 %j.0, 1 %cmp2 = icmp slt i32 %inc, %b br i1 %cmp2, label %do.body1, label %do.end ; CHECK: edge if.end -> do.body1 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge if.end -> do.end probability is 0x04000000 / 0x80000000 = 3.12% do.end: call void @g3() %inc4 = add nsw i32 %i.0, 1 %cmp5 = icmp slt i32 %inc4, %a br i1 %cmp5, label %do.body, label %do.end6 ; CHECK: edge do.end -> do.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.end -> do.end6 probability is 0x04000000 / 0x80000000 = 3.12% do.end6: call void @g4() br label %return ; CHECK: edge do.end6 -> return probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] return: ret void } define void @test6(i32 %a, i32 %b, i32* %c) { entry: br label %do.body ; CHECK: edge entry -> do.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body: %i.0 = phi i32 [ 0, %entry ], [ %inc4, %do.end ] call void @g1() br label %do.body1 ; CHECK: edge do.body -> do.body1 probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] do.body1: %j.0 = phi i32 [ 0, %do.body ], [ %inc, %do.cond ] call void @g2() %0 = load i32, i32* %c, align 4 %cmp = icmp slt i32 %0, 42 br i1 %cmp, label %return, label %do.cond ; CHECK: edge do.body1 -> return probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge do.body1 -> do.cond probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] do.cond: %inc = add nsw i32 %j.0, 1 %cmp2 = icmp slt i32 %inc, %b br i1 %cmp2, label %do.body1, label %do.end ; CHECK: edge do.cond -> do.body1 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.cond -> do.end probability is 0x04000000 / 0x80000000 = 3.12% do.end: call void @g3() %inc4 = add nsw i32 %i.0, 1 %cmp5 = icmp slt i32 %inc4, %a br i1 %cmp5, label %do.body, label %do.end6 ; CHECK: edge do.end -> do.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge do.end -> do.end6 probability is 0x04000000 / 0x80000000 = 3.12% do.end6: call void @g4() br label %return ; CHECK: edge do.end6 -> return probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] return: ret void } define void @test7(i32 %a, i32 %b, i32* %c) { entry: %cmp10 = icmp sgt i32 %a, 0 br i1 %cmp10, label %for.body.lr.ph, label %for.end7 ; CHECK: edge entry -> for.body.lr.ph probability is 0x50000000 / 0x80000000 = 62.50% ; CHECK: edge entry -> for.end7 probability is 0x30000000 / 0x80000000 = 37.50% for.body.lr.ph: %cmp38 = icmp sgt i32 %b, 0 br label %for.body ; CHECK: edge for.body.lr.ph -> for.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.body: %i.011 = phi i32 [ 0, %for.body.lr.ph ], [ %inc6, %for.inc5 ] %0 = load i32, i32* %c, align 4 %cmp1 = icmp eq i32 %0, %i.011 br i1 %cmp1, label %for.inc5, label %if.end ; CHECK: edge for.body -> for.inc5 probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge for.body -> if.end probability is 0x40000000 / 0x80000000 = 50.00% if.end: call void @g1() br i1 %cmp38, label %for.body4, label %for.end ; CHECK: edge if.end -> for.body4 probability is 0x50000000 / 0x80000000 = 62.50% ; CHECK: edge if.end -> for.end probability is 0x30000000 / 0x80000000 = 37.50% for.body4: %j.09 = phi i32 [ %inc, %for.body4 ], [ 0, %if.end ] call void @g2() %inc = add nsw i32 %j.09, 1 %exitcond = icmp eq i32 %inc, %b br i1 %exitcond, label %for.end, label %for.body4 ; CHECK: edge for.body4 -> for.end probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge for.body4 -> for.body4 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] for.end: call void @g3() br label %for.inc5 ; CHECK: edge for.end -> for.inc5 probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.inc5: %inc6 = add nsw i32 %i.011, 1 %exitcond12 = icmp eq i32 %inc6, %a br i1 %exitcond12, label %for.end7, label %for.body ; CHECK: edge for.inc5 -> for.end7 probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge for.inc5 -> for.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] for.end7: call void @g4() ret void } define void @test8(i32 %a, i32 %b, i32* %c) { entry: %cmp18 = icmp sgt i32 %a, 0 br i1 %cmp18, label %for.body.lr.ph, label %for.end15 ; CHECK: edge entry -> for.body.lr.ph probability is 0x50000000 / 0x80000000 = 62.50% ; CHECK: edge entry -> for.end15 probability is 0x30000000 / 0x80000000 = 37.50% for.body.lr.ph: %cmp216 = icmp sgt i32 %b, 0 %arrayidx5 = getelementptr inbounds i32, i32* %c, i64 1 %arrayidx9 = getelementptr inbounds i32, i32* %c, i64 2 br label %for.body ; CHECK: edge for.body.lr.ph -> for.body probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.body: %i.019 = phi i32 [ 0, %for.body.lr.ph ], [ %inc14, %for.end ] call void @g1() br i1 %cmp216, label %for.body3, label %for.end ; CHECK: edge for.body -> for.body3 probability is 0x50000000 / 0x80000000 = 62.50% ; CHECK: edge for.body -> for.end probability is 0x30000000 / 0x80000000 = 37.50% for.body3: %j.017 = phi i32 [ 0, %for.body ], [ %inc, %for.inc ] %0 = load i32, i32* %c, align 4 %cmp4 = icmp eq i32 %0, %j.017 br i1 %cmp4, label %for.inc, label %if.end ; CHECK: edge for.body3 -> for.inc probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge for.body3 -> if.end probability is 0x40000000 / 0x80000000 = 50.00% if.end: %1 = load i32, i32* %arrayidx5, align 4 %cmp6 = icmp eq i32 %1, %j.017 br i1 %cmp6, label %for.inc, label %if.end8 ; CHECK: edge if.end -> for.inc probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge if.end -> if.end8 probability is 0x40000000 / 0x80000000 = 50.00% if.end8: %2 = load i32, i32* %arrayidx9, align 4 %cmp10 = icmp eq i32 %2, %j.017 br i1 %cmp10, label %for.inc, label %if.end12 ; CHECK: edge if.end8 -> for.inc probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge if.end8 -> if.end12 probability is 0x40000000 / 0x80000000 = 50.00% if.end12: call void @g2() br label %for.inc ; CHECK: edge if.end12 -> for.inc probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.inc: %inc = add nsw i32 %j.017, 1 %exitcond = icmp eq i32 %inc, %b br i1 %exitcond, label %for.end, label %for.body3 ; CHECK: edge for.inc -> for.end probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge for.inc -> for.body3 probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] for.end: call void @g3() %inc14 = add nsw i32 %i.019, 1 %exitcond20 = icmp eq i32 %inc14, %a br i1 %exitcond20, label %for.end15, label %for.body ; CHECK: edge for.end -> for.end15 probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge for.end -> for.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] for.end15: call void @g4() ret void } ; Test that an irreducible loop gets heavily weighted back-edges. define void @test9(i32 %i, i32 %x, i32 %c) { entry: %tobool = icmp eq i32 %c, 0 br i1 %tobool, label %if.end, label %midloop ; CHECK: edge entry -> if.end probability is 0x30000000 / 0x80000000 = 37.50% ; CHECK: edge entry -> midloop probability is 0x50000000 / 0x80000000 = 62.50% if.end: br label %for.cond ; CHECK: edge if.end -> for.cond probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.cond: %i.addr.0 = phi i32 [ %inc, %for.inc ], [ 0, %if.end ] %cmp = icmp slt i32 %i.addr.0, %x br i1 %cmp, label %midloop, label %end ; CHECK: edge for.cond -> midloop probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge for.cond -> end probability is 0x04000000 / 0x80000000 = 3.12% midloop: %i.addr.1 = phi i32 [ %i, %entry ], [ %i.addr.0, %for.cond ] %call1 = call i32 @g5() %tobool2 = icmp eq i32 %call1, 0 br i1 %tobool2, label %for.inc, label %end ; CHECK: edge midloop -> for.inc probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge midloop -> end probability is 0x04000000 / 0x80000000 = 3.12% for.inc: %inc = add nsw i32 %i.addr.1, 1 br label %for.cond ; CHECK: edge for.inc -> for.cond probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] end: ret void } ; Check that the for.body -> if.then edge is considered unlikely due to making ; the if-condition false for the next iteration of the loop. define i32 @test10(i32 %n, i32* %p) { entry: br label %for.cond ; CHECK: edge entry -> for.cond probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.cond: %count.0 = phi i32 [ 0, %entry ], [ %count.1, %for.inc ] %sum.0 = phi i32 [ 0, %entry ], [ %sum.1, %for.inc ] %i.0 = phi i32 [ 0, %entry ], [ %inc3, %for.inc ] %cmp = icmp slt i32 %i.0, %n br i1 %cmp, label %for.body, label %for.cond.cleanup ; CHECK: edge for.cond -> for.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge for.cond -> for.cond.cleanup probability is 0x04000000 / 0x80000000 = 3.12% for.cond.cleanup: ret i32 %sum.0 for.body: %arrayidx = getelementptr inbounds i32, i32* %p, i32 %i.0 %0 = load i32, i32* %arrayidx, align 4 %add = add nsw i32 %sum.0, %0 %inc = add nsw i32 %count.0, 1 %cmp1 = icmp sgt i32 %count.0, 6 br i1 %cmp1, label %if.then, label %for.inc ; CHECK: edge for.body -> if.then probability is 0x2aaaa8e4 / 0x80000000 = 33.33% ; CHECK: edge for.body -> for.inc probability is 0x5555571c / 0x80000000 = 66.67% if.then: store i32 %add, i32* %arrayidx, align 4 br label %for.inc ; CHECK: edge if.then -> for.inc probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.inc: %count.1 = phi i32 [ 0, %if.then ], [ %inc, %for.body ] %sum.1 = phi i32 [ 0, %if.then ], [ %add, %for.body ] %inc3 = add nsw i32 %i.0, 1 br label %for.cond ; CHECK: edge for.inc -> for.cond probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] } ; Each successor to for.body makes itself not be taken in the next iteration, so ; both should be equally likely define i32 @test11(i32 %n, i32* %p) { entry: br label %for.cond ; CHECK: edge entry -> for.cond probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.cond: %flip.0 = phi i32 [ 0, %entry ], [ %flip.1, %for.inc ] %sum.0 = phi i32 [ 0, %entry ], [ %sum.1, %for.inc ] %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ] %cmp = icmp slt i32 %i.0, %n br i1 %cmp, label %for.body, label %for.cond.cleanup ; CHECK: edge for.cond -> for.body probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge for.cond -> for.cond.cleanup probability is 0x04000000 / 0x80000000 = 3.12% for.cond.cleanup: ret i32 %sum.0 for.body: %tobool = icmp eq i32 %flip.0, 0 %arrayidx1 = getelementptr inbounds i32, i32* %p, i32 %i.0 %0 = load i32, i32* %arrayidx1, align 4 br i1 %tobool, label %if.else, label %if.then ; CHECK: edge for.body -> if.else probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge for.body -> if.then probability is 0x40000000 / 0x80000000 = 50.00% if.then: %add = add nsw i32 %0, %sum.0 store i32 %add, i32* %arrayidx1, align 4 br label %for.inc ; CHECK: edge if.then -> for.inc probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] if.else: %add2 = add nsw i32 %sum.0, %0 br label %for.inc ; CHECK: edge if.else -> for.inc probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] for.inc: %flip.1 = phi i32 [ 0, %if.then ], [ 1, %if.else ] %sum.1 = phi i32 [ %sum.0, %if.then ], [ %add2, %if.else ] %inc = add nsw i32 %i.0, 1 br label %for.cond ; CHECK: edge for.inc -> for.cond probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] } ; The loop heuristic should not overwrite the invoke heuristic. The unwind destination ; of an invoke should be considered VERY rare even in a loop. define void @test12(i32 %a) personality i8 0 { entry: br label %loop ; CHECK: edge entry -> loop probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] loop: %i.0 = phi i32 [ 0, %entry ], [ %inc, %invoke.cont ] invoke i32 @InvokeCall() to label %invoke.cont unwind label %lpad ; CHECK: edge loop -> invoke.cont probability is 0x7ffff800 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge loop -> lpad probability is 0x00000800 / 0x80000000 = 0.00% invoke.cont: %inc = add nsw i32 %i.0, 1 %cmp = icmp slt i32 %inc, %a br i1 %cmp, label %loop, label %exit ; CHECK: edge invoke.cont -> loop probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge invoke.cont -> exit probability is 0x04000000 / 0x80000000 = 3.12% lpad: %ll = landingpad { i8*, i32 } cleanup br label %exit exit: ret void } declare i32 @InvokeCall() declare void @cold() cold ; If loop has single exit and it leads to 'cold' block then edge leading to loop enter ; should be considered 'cold' as well. define void @test13() { ; CHECK: edge entry -> loop probability is 0x078780e3 / 0x80000000 = 5.88% ; CHECK: edge entry -> exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge] ; CHECK: edge loop -> loop probability is 0x7fbe1203 / 0x80000000 = 99.80% [HOT edge] ; CHECK: edge loop -> cold probability is 0x0041edfd / 0x80000000 = 0.20% ; CHECK: edge cold -> exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] entry: br i1 undef, label %loop, label %exit loop: %i.0 = phi i32 [ 0, %entry ], [ %inc, %loop ] %inc = add nsw i32 %i.0, 1 br i1 undef, label %loop, label %cold cold: call void @cold() br label %exit exit: ret void } ; This is the same case as test13 but with additional loop 'preheader' block. define void @test14() { ; CHECK: edge entry -> preheader probability is 0x078780e3 / 0x80000000 = 5.88% ; CHECK: edge entry -> exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge] ; CHECK: edge preheader -> loop probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge loop -> loop probability is 0x7fbe1203 / 0x80000000 = 99.80% [HOT edge] ; CHECK: edge loop -> cold probability is 0x0041edfd / 0x80000000 = 0.20% ; CHECK: edge cold -> exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] entry: br i1 undef, label %preheader, label %exit preheader: br label %loop loop: %i.0 = phi i32 [ 0, %preheader ], [ %inc, %loop ] %inc = add nsw i32 %i.0, 1 br i1 undef, label %loop, label %cold cold: call void @cold() br label %exit exit: ret void } ; If loop has multiple low probability exits then edge leading to loop enter ; should be considered low probable as well. define void @test15() { ; CHECK: edge entry -> loop probability is 0x078780e3 / 0x80000000 = 5.88% ; CHECK: edge entry -> exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge] ; CHECK: edge loop -> cont probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge loop -> unreached probability is 0x00000000 / 0x80000000 = 0.00% ; CHECK: edge cont -> loop probability is 0x7fbe1203 / 0x80000000 = 99.80% [HOT edge] ; CHECK: edge cont -> cold probability is 0x0041edfd / 0x80000000 = 0.20% ; CHECK: edge cold -> exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] entry: br i1 undef, label %loop, label %exit loop: %i.0 = phi i32 [ 0, %entry ], [ %inc, %cont ] %inc = add nsw i32 %i.0, 1 br i1 undef, label %cont, label %unreached cont: br i1 undef, label %loop, label %cold unreached: unreachable cold: call void @cold() br label %exit exit: ret void } ; This is the same case as test15 but with additional loop 'preheader' block. define void @test16() { ; CHECK: edge entry -> preheader probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge preheader -> loop probability is 0x078780e3 / 0x80000000 = 5.88% ; CHECK: edge preheader -> exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge] ; CHECK: edge loop -> cont probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge loop -> unreached probability is 0x00000000 / 0x80000000 = 0.00% ; CHECK: edge cont -> loop probability is 0x7fbe1203 / 0x80000000 = 99.80% [HOT edge] ; CHECK: edge cont -> cold probability is 0x0041edfd / 0x80000000 = 0.20% ; CHECK: edge cold -> exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] entry: br label %preheader preheader: br i1 undef, label %loop, label %exit loop: %i.0 = phi i32 [ 0, %preheader ], [ %inc, %cont ] %inc = add nsw i32 %i.0, 1 br i1 undef, label %cont, label %unreached cont: br i1 undef, label %loop, label %cold unreached: unreachable cold: call void @cold() br label %exit exit: ret void } declare void @abort() noreturn ; Check that 'preheader' has 50/50 probability since there is one 'normal' exit. ; Check that exit to 'cold' and 'noreturn' has lower probability than 'normal' exit. define void @test17() { ; CHECK: edge entry -> preheader probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge preheader -> loop probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge preheader -> exit probability is 0x40000000 / 0x80000000 = 50.00% ; CHECK: edge loop -> cont probability is 0x7ffff800 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge loop -> noreturn probability is 0x00000800 / 0x80000000 = 0.00% ; CHECK: edge cont -> cont2 probability is 0x7fbe1203 / 0x80000000 = 99.80% [HOT edge] ; CHECK: edge cont -> cold probability is 0x0041edfd / 0x80000000 = 0.20% ; CHECK: edge cont2 -> loop probability is 0x7c000000 / 0x80000000 = 96.88% [HOT edge] ; CHECK: edge cont2 -> exit probability is 0x04000000 / 0x80000000 = 3.12% ; CHECK: edge cold -> exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] entry: br label %preheader preheader: br i1 undef, label %loop, label %exit loop: %i.0 = phi i32 [ 0, %preheader ], [ %inc, %cont2 ] %inc = add nsw i32 %i.0, 1 br i1 undef, label %cont, label %noreturn cont: br i1 undef, label %cont2, label %cold cont2: br i1 undef, label %loop, label %exit noreturn: call void @abort() unreachable cold: call void @cold() br label %exit exit: ret void } ; This is case with two loops where one nested into another. Nested loop has ; low probable exit what encreases robability to take exit in the top level loop. define void @test18() { ; CHECK: edge entry -> top.loop probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] ; CHECK: edge top.loop -> loop probability is 0x546cd4b7 / 0x80000000 = 65.96% ; CHECK: edge top.loop -> exit probability is 0x2b932b49 / 0x80000000 = 34.04% ; CHECK: edge loop -> loop probability is 0x7fbe1203 / 0x80000000 = 99.80% [HOT edge] ; CHECK: edge loop -> cold probability is 0x0041edfd / 0x80000000 = 0.20% ; CHECK: edge cold -> top.loop probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge] entry: br label %top.loop top.loop: %j.0 = phi i32 [ 0, %entry ], [ %j.inc, %cold ] br i1 undef, label %loop, label %exit loop: %i.0 = phi i32 [ %j.0, %top.loop ], [ %inc, %loop ] %inc = add nsw i32 %i.0, 1 br i1 undef, label %loop, label %cold cold: call void @cold() %j.inc = add nsw i32 %j.0, 1 br label %top.loop exit: ret void }