https://github.com/OCHyams updated https://github.com/llvm/llvm-project/pull/134645
>From e3c271ebbf4792bf684acef2af8fbc9df9a9b596 Mon Sep 17 00:00:00 2001 From: Orlando Cazalet-Hyams <orlando.hy...@sony.com> Date: Thu, 3 Apr 2025 18:49:32 +0100 Subject: [PATCH 1/2] [KeyInstr][Clang] While stmt atom See test comment for possible future improvement. This patch is part of a stack that teaches Clang to generate Key Instructions metadata for C and C++. The Key Instructions project is introduced, including a "quick summary" section at the top which adds context for this PR, here: https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668 The feature is only functional in LLVM if LLVM is built with CMake flag LLVM_EXPERIMENTAL_KEY_INSTRUCTIONs. Eventually that flag will be removed. The Clang-side work is demoed here: https://github.com/llvm/llvm-project/pull/130943 --- clang/lib/CodeGen/CGStmt.cpp | 9 +++++- clang/test/DebugInfo/KeyInstructions/while.c | 34 ++++++++++++++++++++ 2 files changed, 42 insertions(+), 1 deletion(-) create mode 100644 clang/test/DebugInfo/KeyInstructions/while.c diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp index e46cfb433ab89..d9fd406ad64ee 100644 --- a/clang/lib/CodeGen/CGStmt.cpp +++ b/clang/lib/CodeGen/CGStmt.cpp @@ -1130,7 +1130,14 @@ void CodeGenFunction::EmitWhileStmt(const WhileStmt &S, if (!Weights && CGM.getCodeGenOpts().OptimizationLevel) BoolCondVal = emitCondLikelihoodViaExpectIntrinsic( BoolCondVal, Stmt::getLikelihood(S.getBody())); - Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock, Weights); + auto *I = Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock, Weights); + // Key Instructions: Emit the condition and branch as separate atoms to + // match existing loop stepping behaviour. FIXME: We could have the branch + // as the backup location for the condition, which would probably be a + // better experience. Explore this later. + if (auto *I = dyn_cast<llvm::Instruction>(BoolCondVal)) + addInstToNewSourceAtom(I, nullptr); + addInstToNewSourceAtom(I, nullptr); if (ExitBlock != LoopExit.getBlock()) { EmitBlock(ExitBlock); diff --git a/clang/test/DebugInfo/KeyInstructions/while.c b/clang/test/DebugInfo/KeyInstructions/while.c new file mode 100644 index 0000000000000..f1bb91520315a --- /dev/null +++ b/clang/test/DebugInfo/KeyInstructions/while.c @@ -0,0 +1,34 @@ +// RUN: %clang -gkey-instructions -x c++ -std=c++17 %s -gmlt -S -emit-llvm -o - \ +// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank + +// RUN: %clang -gkey-instructions -x c %s -gmlt -S -emit-llvm -o - \ +// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank + +// Perennial quesiton: should the `dec` be in its own source atom or not +// (currently it is). + +// We've made the cmp and br separate source atoms for now, to match existing +// behaviour in this case: +// 1. while ( +// 2. int i = --End +// 3. ) { +// 4. useValue(i); +// 5. } +// Without Key Instructions we go: 2, 1[, 4, 2, 1]+ +// Without separating cmp and br with Key Instructions we'd get: +// 1[, 4, 1]+. If we made the cmp higher precedence than the +// br and had them in the same group, we could get: +// 2, [4, 2]+ which might be nicer. FIXME: do that later. + +void a(int A) { +// CHECK: %dec = add nsw i32 %0, -1, !dbg [[G1R2:!.*]] +// CHECK: store i32 %dec, ptr %A.addr{{.*}}, !dbg [[G1R1:!.*]] +// CHECK: %tobool = icmp ne i32 %dec, 0, !dbg [[G2R1:!.*]] +// CHECK: br i1 %tobool, label %while.body, label %while.end, !dbg [[G3R1:!.*]] + while (--A) { }; +} + +// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2) +// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1) +// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1) +// CHECK: [[G3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1) >From cdd6ff398508e486bd669f9a441e557824699a98 Mon Sep 17 00:00:00 2001 From: Orlando Cazalet-Hyams <orlando.hy...@sony.com> Date: Wed, 21 May 2025 15:47:54 +0100 Subject: [PATCH 2/2] cc1 --- clang/test/DebugInfo/KeyInstructions/while.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/clang/test/DebugInfo/KeyInstructions/while.c b/clang/test/DebugInfo/KeyInstructions/while.c index f1bb91520315a..d876bd1d93792 100644 --- a/clang/test/DebugInfo/KeyInstructions/while.c +++ b/clang/test/DebugInfo/KeyInstructions/while.c @@ -1,7 +1,7 @@ -// RUN: %clang -gkey-instructions -x c++ -std=c++17 %s -gmlt -S -emit-llvm -o - \ +// RUN: %clang_cc1 -gkey-instructions -x c++ -std=c++17 %s -debug-info-kind=line-tables-only -emit-llvm -o - \ // RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank -// RUN: %clang -gkey-instructions -x c %s -gmlt -S -emit-llvm -o - \ +// RUN: %clang_cc1 -gkey-instructions -x c %s -debug-info-kind=line-tables-only -emit-llvm -o - \ // RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank // Perennial quesiton: should the `dec` be in its own source atom or not _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
