https://github.com/mtrofin updated https://github.com/llvm/llvm-project/pull/164507
>From 577971fd0c10a2733c3255609f5cb7db874011a4 Mon Sep 17 00:00:00 2001 From: Mircea Trofin <[email protected]> Date: Tue, 21 Oct 2025 15:20:14 -0700 Subject: [PATCH] [LVer][profcheck] explicitly set unknown branch weights for the versioned/unversioned selector --- llvm/lib/Transforms/Utils/LoopVersioning.cpp | 10 ++++++++-- .../Transforms/LoopDistribute/basic-with-memchecks.ll | 5 +++-- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/llvm/lib/Transforms/Utils/LoopVersioning.cpp b/llvm/lib/Transforms/Utils/LoopVersioning.cpp index ec2e6c1ab796b..4786819d18fa4 100644 --- a/llvm/lib/Transforms/Utils/LoopVersioning.cpp +++ b/llvm/lib/Transforms/Utils/LoopVersioning.cpp @@ -23,6 +23,7 @@ #include "llvm/IR/Dominators.h" #include "llvm/IR/MDBuilder.h" #include "llvm/IR/PassManager.h" +#include "llvm/IR/ProfDataUtils.h" #include "llvm/Support/CommandLine.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/Cloning.h" @@ -109,8 +110,13 @@ void LoopVersioning::versionLoop( // Insert the conditional branch based on the result of the memchecks. Instruction *OrigTerm = RuntimeCheckBB->getTerminator(); Builder.SetInsertPoint(OrigTerm); - Builder.CreateCondBr(RuntimeCheck, NonVersionedLoop->getLoopPreheader(), - VersionedLoop->getLoopPreheader()); + auto *BI = + Builder.CreateCondBr(RuntimeCheck, NonVersionedLoop->getLoopPreheader(), + VersionedLoop->getLoopPreheader()); + // We don't know what the probability of executing the versioned vs the + // unversioned variants is. + setExplicitlyUnknownBranchWeightsIfProfiled( + *BI, *BI->getParent()->getParent(), DEBUG_TYPE); OrigTerm->eraseFromParent(); // The loops merge in the original exit block. This is now dominated by the diff --git a/llvm/test/Transforms/LoopDistribute/basic-with-memchecks.ll b/llvm/test/Transforms/LoopDistribute/basic-with-memchecks.ll index 97ea2c6708dad..2828882afe779 100644 --- a/llvm/test/Transforms/LoopDistribute/basic-with-memchecks.ll +++ b/llvm/test/Transforms/LoopDistribute/basic-with-memchecks.ll @@ -28,7 +28,7 @@ target triple = "x86_64-apple-macosx10.10.0" @E = common global ptr null, align 8 ; CHECK-LABEL: @f( -define void @f() { +define void @f() !prof !{!"function_entry_count", i32 10} { entry: %a = load ptr, ptr @A, align 8 %b = load ptr, ptr @B, align 8 @@ -55,7 +55,7 @@ entry: ; CHECK: = icmp ; CHECK-NOT: = icmp -; CHECK: br i1 %conflict.rdx15, label %for.body.ph.lver.orig, label %for.body.ph.ldist1 +; CHECK: br i1 %conflict.rdx15, label %for.body.ph.lver.orig, label %for.body.ph.ldist1, !prof ![[PROF1:[0-9]]] ; The non-distributed loop that the memchecks fall back on. @@ -289,3 +289,4 @@ attributes #1 = { nounwind convergent } !0 = distinct !{!0, !1} !1 = !{!"llvm.loop.distribute.enable", i1 true} +; CHECK: ![[PROF1]] = !{!"unknown", !"loop-versioning"} _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
