[KeyInstr][Clang] Assignment atom group #134637
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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: #130943
This was referenced Apr 7, 2025
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This was referenced Apr 7, 2025
This was referenced Apr 7, 2025
This was referenced Apr 7, 2025
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@llvm/pr-subscribers-clang-codegen @llvm/pr-subscribers-clang Author: Orlando Cazalet-Hyams (OCHyams) Changes[KeyInstr][Clang] Assignment atom group This patch is part of a stack that teaches Clang to generate Key Instructions The Key Instructions project is introduced, including a "quick summary" section The feature is only functional in LLVM if LLVM is built with CMake flag The Clang-side work is demoed here: [KeyInstr][Clang] Multiple assignment (x = y = z) Compound assign Pre/Post Inc/Dec Rename test & run C & C++ Full diff: https://github.com/llvm/llvm-project/pull/134637.diff 4 Files Affected:
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index a00a8ba2cd5cb..7408c498b3a1a 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -5814,6 +5814,15 @@ LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
assert(E->getOpcode() == BO_Assign && "unexpected binary l-value");
+ // This covers both LHS and RHS expressions, though nested RHS
+ // expressions may get subsequently separately grouped.
+ // FIXME(OCH): Not clear yet if we've got fine enough control
+ // to pick and choose when we need to. Currently looks ok:
+ // a = b = c -> Two atoms.
+ // x = new(1) -> One atom (for both addr store and value store).
+ // Complex and agg assignment -> One atom.
+ ApplyAtomGroup Grp(getDebugInfo());
+
// Note that in all of these cases, __block variables need the RHS
// evaluated first just in case the variable gets moved by the RHS.
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 140a12d384502..a4afafd3f536b 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -897,6 +897,7 @@ class ScalarExprEmitter
return result; \
} \
Value *VisitBin##OP##Assign(const CompoundAssignOperator *E) { \
+ ApplyAtomGroup Grp(CGF.getDebugInfo()); \
return EmitCompoundAssign(E, &ScalarExprEmitter::Emit##OP); \
}
HANDLEBINOP(Mul)
@@ -2940,6 +2941,7 @@ class OMPLastprivateConditionalUpdateRAII {
llvm::Value *
ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
bool isInc, bool isPre) {
+ ApplyAtomGroup Grp(CGF.getDebugInfo());
OMPLastprivateConditionalUpdateRAII OMPRegion(CGF, E);
QualType type = E->getSubExpr()->getType();
llvm::PHINode *atomicPHI = nullptr;
@@ -4973,6 +4975,7 @@ llvm::Value *CodeGenFunction::EmitWithOriginalRHSBitfieldAssignment(
}
Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
+ ApplyAtomGroup Grp(CGF.getDebugInfo());
bool Ignore = TestAndClearIgnoreResultAssign();
Value *RHS;
@@ -5740,6 +5743,7 @@ LValue CodeGenFunction::EmitObjCIsaExpr(const ObjCIsaExpr *E) {
LValue CodeGenFunction::EmitCompoundAssignmentLValue(
const CompoundAssignOperator *E) {
+ ApplyAtomGroup Grp(getDebugInfo());
ScalarExprEmitter Scalar(*this);
Value *Result = nullptr;
switch (E->getOpcode()) {
diff --git a/clang/test/KeyInstructions/assign-scalar.c b/clang/test/KeyInstructions/assign-scalar.c
new file mode 100644
index 0000000000000..1f1fe8fda39e6
--- /dev/null
+++ b/clang/test/KeyInstructions/assign-scalar.c
@@ -0,0 +1,48 @@
+// RUN: %clang -gkey-instructions -x c++ %s -gmlt -gcolumn-info -S -emit-llvm -o - -Wno-unused-variable \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -x c %s -gmlt -gcolumn-info -S -emit-llvm -o - -Wno-unused-variable \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+unsigned long long g;
+void fun() {
+// CHECK: store i64 0, ptr @g{{.*}}, !dbg [[G1R1:!.*]]
+ g = 0;
+
+// Treat the two assignments as two atoms.
+//
+// FIXME: Because of the atomGroup implementation the load can only be
+// associated with one of the two stores, despite being a good backup
+// loction for both.
+// CHECK-NEXT: %0 = load i64, ptr @g{{.*}}, !dbg [[G2R2:!.*]]
+// CHECK-NEXT: store i64 %0, ptr @g{{.*}}, !dbg [[G3R1:!.*]]
+// CHECK-NEXT: store i64 %0, ptr @g{{.*}}, !dbg [[G2R1:!.*]]
+ g = g = g;
+
+// Compound assignment.
+// CHECK: %1 = load i64, ptr @g
+// CHECK: %add = add i64 %1, 50, !dbg [[G4R2:!.*]]
+// CHECK: store i64 %add, ptr @g{{.*}}, !dbg [[G4R1:!.*]]
+ g += 50;
+
+// Pre/Post Inc/Dec.
+// CHECK: %2 = load i64, ptr @g
+// CHECK: %inc = add i64 %2, 1, !dbg [[G5R2:!.*]]
+// CHECK: store i64 %inc, ptr @g{{.*}}, !dbg [[G5R1:!.*]]
+ ++g;
+// CHECK: %3 = load i64, ptr @g
+// CHECK: %dec = add i64 %3, -1, !dbg [[G6R2:!.*]]
+// CHECK: store i64 %dec, ptr @g{{.*}}, !dbg [[G6R1:!.*]]
+ g--;
+}
+
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G2R2]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 2)
+// CHECK: [[G3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)
+// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
+// CHECK: [[G4R2]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 2)
+// CHECK: [[G4R1]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 1)
+// CHECK: [[G5R2]] = !DILocation({{.*}}, atomGroup: 5, atomRank: 2)
+// CHECK: [[G5R1]] = !DILocation({{.*}}, atomGroup: 5, atomRank: 1)
+// CHECK: [[G6R2]] = !DILocation({{.*}}, atomGroup: 6, atomRank: 2)
+// CHECK: [[G6R1]] = !DILocation({{.*}}, atomGroup: 6, atomRank: 1)
diff --git a/clang/test/KeyInstructions/init-agg.cpp b/clang/test/KeyInstructions/init-agg.c
similarity index 83%
rename from clang/test/KeyInstructions/init-agg.cpp
rename to clang/test/KeyInstructions/init-agg.c
index f0cc67e659d95..ad298715286cd 100644
--- a/clang/test/KeyInstructions/init-agg.cpp
+++ b/clang/test/KeyInstructions/init-agg.c
@@ -1,5 +1,8 @@
-// RUN: %clang -gkey-instructions %s -gmlt -gno-column-info -S -emit-llvm -o - -ftrivial-auto-var-init=pattern \
+// RUN: %clang -gkey-instructions -x c++ %s -gmlt -gno-column-info -S -emit-llvm -o - -ftrivial-auto-var-init=pattern \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -x c %s -gmlt -gno-column-info -S -emit-llvm -o - -ftrivial-auto-var-init=pattern \
// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
// The implicit-check-not is important; we don't want the GEPs created for the
@@ -7,7 +10,6 @@
int g;
void a() {
-// CHECK: _Z1av()
// CHECK: call void @llvm.memcpy{{.*}}, !dbg [[G1R1:!.*]]
int A[] = { 1, 2, 3 };
|
This was referenced Apr 7, 2025
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[KeyInstr][Clang] Assignment atom group
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:
#130943
[KeyInstr][Clang] Multiple assignment (x = y = z)
Compound assign
Pre/Post Inc/Dec
Rename test & run C & C++