[llvm-branch-commits] [clang] [KeyInstr][Clang] For range stmt atoms (PR #134647)
Orlando Cazalet-Hyams via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Mon Apr 7 06:48:08 PDT 2025
https://github.com/OCHyams created https://github.com/llvm/llvm-project/pull/134647
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
>From 2484a49c8f259891882a18636b769bf4c06cb8ce Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Thu, 3 Apr 2025 19:46:01 +0100
Subject: [PATCH] [KeyInstr][Clang] For range stmt atoms
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 | 13 ++++-
clang/test/KeyInstructions/for-range.cpp | 72 ++++++++++++++++++++++++
2 files changed, 84 insertions(+), 1 deletion(-)
create mode 100644 clang/test/KeyInstructions/for-range.cpp
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 65b71c39d86c4..9292be24fc12e 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -1477,7 +1477,14 @@ CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
if (!Weights && CGM.getCodeGenOpts().OptimizationLevel)
BoolCondVal = emitCondLikelihoodViaExpectIntrinsic(
BoolCondVal, Stmt::getLikelihood(S.getBody()));
- Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);
+ auto *I = Builder.CreateCondBr(BoolCondVal, ForBody, 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.
+ if (auto *I = dyn_cast<llvm::Instruction>(BoolCondVal))
+ addInstToNewSourceAtom(I, nullptr);
+ addInstToNewSourceAtom(I, nullptr);
if (ExitBlock != LoopExit.getBlock()) {
EmitBlock(ExitBlock);
@@ -1526,6 +1533,10 @@ CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
if (CGM.shouldEmitConvergenceTokens())
ConvergenceTokenStack.pop_back();
+
+ // We want the for closing brace to be step-able on to match existing
+ // behaviour.
+ addInstToNewSourceAtom(ForBody->getTerminator(), nullptr);
}
void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
diff --git a/clang/test/KeyInstructions/for-range.cpp b/clang/test/KeyInstructions/for-range.cpp
new file mode 100644
index 0000000000000..be71d9fbfb581
--- /dev/null
+++ b/clang/test/KeyInstructions/for-range.cpp
@@ -0,0 +1,72 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5
+// RUN: %clang -gkey-instructions %s -gmlt -S -emit-llvm -o - \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// Perennial quesiton: should the inc be its own source atom or not
+// (currently it is).
+
+// FIXME: See do.c and while.c regarding cmp and cond br groups.
+
+// The stores in the setup (stores to __RANGE1, __BEGIN1, __END1) are all
+// marked as Key. Unclear whether that's desirable. Keep for now as that's
+// least risky.
+
+// Check the conditional branch (and the condition) in FOR_COND and
+// unconditional branch in FOR_BODY are Key Instructions.
+
+struct Range {
+ int *begin();
+ int *end();
+} r;
+
+// CHECK-LABEL: define dso_local void @_Z1av(
+// CHECK-SAME: ) #[[ATTR0:[0-9]+]] !dbg [[DBG10:![0-9]+]] {
+// CHECK-NEXT: [[ENTRY:.*:]]
+// CHECK-NEXT: [[__RANGE1:%.*]] = alloca ptr, align 8
+// CHECK-NEXT: [[__BEGIN1:%.*]] = alloca ptr, align 8
+// CHECK-NEXT: [[__END1:%.*]] = alloca ptr, align 8
+// CHECK-NEXT: [[I:%.*]] = alloca i32, align 4
+// CHECK-NEXT: store ptr @r, ptr [[__RANGE1]], align 8, !dbg [[DBG14:![0-9]+]]
+// CHECK-NEXT: [[CALL:%.*]] = call noundef ptr @_ZN5Range5beginEv(ptr noundef nonnull align 1 dereferenceable(1) @r), !dbg [[DBG15:![0-9]+]]
+// CHECK-NEXT: store ptr [[CALL]], ptr [[__BEGIN1]], align 8, !dbg [[DBG16:![0-9]+]]
+// CHECK-NEXT: [[CALL1:%.*]] = call noundef ptr @_ZN5Range3endEv(ptr noundef nonnull align 1 dereferenceable(1) @r), !dbg [[DBG17:![0-9]+]]
+// CHECK-NEXT: store ptr [[CALL1]], ptr [[__END1]], align 8, !dbg [[DBG18:![0-9]+]]
+// CHECK-NEXT: br label %[[FOR_COND:.*]], !dbg [[DBG19:![0-9]+]]
+// CHECK: [[FOR_COND]]:
+// CHECK-NEXT: [[TMP0:%.*]] = load ptr, ptr [[__BEGIN1]], align 8, !dbg [[DBG19]]
+// CHECK-NEXT: [[TMP1:%.*]] = load ptr, ptr [[__END1]], align 8, !dbg [[DBG19]]
+// CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[TMP0]], [[TMP1]], !dbg [[DBG20:![0-9]+]]
+// CHECK-NEXT: br i1 [[CMP]], label %[[FOR_BODY:.*]], label %[[FOR_END:.*]], !dbg [[DBG21:![0-9]+]]
+// CHECK: [[FOR_BODY]]:
+// CHECK-NEXT: [[TMP2:%.*]] = load ptr, ptr [[__BEGIN1]], align 8, !dbg [[DBG19]]
+// CHECK-NEXT: [[TMP3:%.*]] = load i32, ptr [[TMP2]], align 4, !dbg [[DBG22:![0-9]+]]
+// CHECK-NEXT: store i32 [[TMP3]], ptr [[I]], align 4, !dbg [[DBG23:![0-9]+]]
+// CHECK-NEXT: br label %[[FOR_INC:.*]], !dbg [[DBG24:![0-9]+]]
+// CHECK: [[FOR_INC]]:
+// CHECK-NEXT: [[TMP4:%.*]] = load ptr, ptr [[__BEGIN1]], align 8, !dbg [[DBG19]]
+// CHECK-NEXT: [[INCDEC_PTR:%.*]] = getelementptr inbounds nuw i32, ptr [[TMP4]], i32 1, !dbg [[DBG25:![0-9]+]]
+// CHECK-NEXT: store ptr [[INCDEC_PTR]], ptr [[__BEGIN1]], align 8, !dbg [[DBG26:![0-9]+]]
+// CHECK-NEXT: br label %[[FOR_COND]], !dbg [[DBG19]], !llvm.loop
+// CHECK: [[FOR_END]]:
+// CHECK-NEXT: ret void, !dbg [[DBG30:![0-9]+]]
+//
+void a() {
+ for (int i: r)
+ ;
+}
+//.
+// CHECK: [[DBG14]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[DBG15]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 2)
+// CHECK: [[DBG16]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
+// CHECK: [[DBG17]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 2)
+// CHECK: [[DBG18]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)
+// CHECK: [[DBG19]] = !DILocation({{.*}})
+// CHECK: [[DBG20]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 1)
+// CHECK: [[DBG21]] = !DILocation({{.*}}, atomGroup: 5, atomRank: 1)
+// CHECK: [[DBG22]] = !DILocation({{.*}}, atomGroup: 6, atomRank: 2)
+// CHECK: [[DBG23]] = !DILocation({{.*}}, atomGroup: 6, atomRank: 1)
+// CHECK: [[DBG24]] = !DILocation({{.*}} atomGroup: 8, atomRank: 1)
+// CHECK: [[DBG25]] = !DILocation({{.*}}, atomGroup: 7, atomRank: 2)
+// CHECK: [[DBG26]] = !DILocation({{.*}}, atomGroup: 7, atomRank: 1)
+// CHECK: [[DBG30]] = !DILocation({{.*}})
+//.
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