[llvm-branch-commits] [clang] [KeyInstr][Clang] Coerced store atoms (PR #134653)

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Mon Apr 7 06:52:57 PDT 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Orlando Cazalet-Hyams (OCHyams)

<details>
<summary>Changes</summary>

[KeyInstr][Clang] Coerced store 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

[KeyInstr][Clang] Coerced to int atom

[KeyInstr][Clang] Coerced ptr to int atom

[KeyInstr][Clang] Coerce packed struct atom

[KeyInstr][Clang] Coerce through memory atom

---
Full diff: https://github.com/llvm/llvm-project/pull/134653.diff


5 Files Affected:

- (modified) clang/lib/CodeGen/CGCall.cpp (+13-8) 
- (added) clang/test/KeyInstructions/coerced-packed.c (+22) 
- (added) clang/test/KeyInstructions/coerced-ptr.c (+21) 
- (added) clang/test/KeyInstructions/coerced-through-memory.c (+26) 
- (added) clang/test/KeyInstructions/coerced.c (+40) 


``````````diff
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index dba3fadba4f60..a794b884a6feb 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1400,7 +1400,8 @@ void CodeGenFunction::CreateCoercedStore(llvm::Value *Src, Address Dst,
         SrcSize == CGM.getDataLayout().getTypeAllocSize(Dst.getElementType())) {
       // If the value is supposed to be a pointer, convert it before storing it.
       Src = CoerceIntOrPtrToIntOrPtr(Src, Dst.getElementType(), *this);
-      Builder.CreateStore(Src, Dst, DstIsVolatile);
+      auto *I = Builder.CreateStore(Src, Dst, DstIsVolatile);
+      addInstToCurrentSourceAtom(I, Src);
     } else if (llvm::StructType *STy =
                    dyn_cast<llvm::StructType>(Src->getType())) {
       // Prefer scalar stores to first-class aggregate stores.
@@ -1408,16 +1409,19 @@ void CodeGenFunction::CreateCoercedStore(llvm::Value *Src, Address Dst,
       for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
         Address EltPtr = Builder.CreateStructGEP(Dst, i);
         llvm::Value *Elt = Builder.CreateExtractValue(Src, i);
-        Builder.CreateStore(Elt, EltPtr, DstIsVolatile);
+        auto *I = Builder.CreateStore(Elt, EltPtr, DstIsVolatile);
+        addInstToCurrentSourceAtom(I, Elt);
       }
     } else {
-      Builder.CreateStore(Src, Dst.withElementType(SrcTy), DstIsVolatile);
+      auto * I = Builder.CreateStore(Src, Dst.withElementType(SrcTy), DstIsVolatile);
+      addInstToCurrentSourceAtom(I, Src);
     }
   } else if (SrcTy->isIntegerTy()) {
     // If the source is a simple integer, coerce it directly.
     llvm::Type *DstIntTy = Builder.getIntNTy(DstSize.getFixedValue() * 8);
     Src = CoerceIntOrPtrToIntOrPtr(Src, DstIntTy, *this);
-    Builder.CreateStore(Src, Dst.withElementType(DstIntTy), DstIsVolatile);
+    auto *I = Builder.CreateStore(Src, Dst.withElementType(DstIntTy), DstIsVolatile);
+    addInstToCurrentSourceAtom(I, Src);
   } else {
     // Otherwise do coercion through memory. This is stupid, but
     // simple.
@@ -1431,10 +1435,11 @@ void CodeGenFunction::CreateCoercedStore(llvm::Value *Src, Address Dst,
     RawAddress Tmp =
         CreateTempAllocaForCoercion(*this, SrcTy, Dst.getAlignment());
     Builder.CreateStore(Src, Tmp);
-    Builder.CreateMemCpy(Dst.emitRawPointer(*this),
-                         Dst.getAlignment().getAsAlign(), Tmp.getPointer(),
-                         Tmp.getAlignment().getAsAlign(),
-                         Builder.CreateTypeSize(IntPtrTy, DstSize));
+    auto *I = Builder.CreateMemCpy(
+        Dst.emitRawPointer(*this), Dst.getAlignment().getAsAlign(),
+        Tmp.getPointer(), Tmp.getAlignment().getAsAlign(),
+        Builder.CreateTypeSize(IntPtrTy, DstSize));
+    addInstToCurrentSourceAtom(I, Src);
   }
 }
 
diff --git a/clang/test/KeyInstructions/coerced-packed.c b/clang/test/KeyInstructions/coerced-packed.c
new file mode 100644
index 0000000000000..476d3f742cec2
--- /dev/null
+++ b/clang/test/KeyInstructions/coerced-packed.c
@@ -0,0 +1,22 @@
+// RUN: %clang -gkey-instructions -gno-column-info -x c++ %s -gmlt -S -emit-llvm -o - -target arm64-apple-ios11 \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -gno-column-info -x c %s -gmlt -S -emit-llvm -o - -target arm64-apple-ios11 \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+typedef struct {
+  char a;
+  int x;
+} __attribute((packed)) S;
+
+S getS();
+void f() {
+// CHECK: [[call:%.*]] = call i40{{.*}}getS{{.*}}, !dbg [[G1R2:!.*]]
+// CHECK: store i40 [[call]], ptr %s, align 1, !dbg [[G1R1:!.*]]
+    S s = getS();
+// CHECK: ret void, !dbg [[G2R1:!.*]]
+}
+
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
diff --git a/clang/test/KeyInstructions/coerced-ptr.c b/clang/test/KeyInstructions/coerced-ptr.c
new file mode 100644
index 0000000000000..4face4bc78a88
--- /dev/null
+++ b/clang/test/KeyInstructions/coerced-ptr.c
@@ -0,0 +1,21 @@
+// RUN: %clang -gkey-instructions -gno-column-info -x c++ %s -gmlt -S -emit-llvm -o - -target x86_64-windows-msvc \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -gno-column-info -x c %s -gmlt -S -emit-llvm -o - -target x86_64-windows-msvc \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+typedef struct { int *p; } Ptr;
+Ptr getPtr();
+void f() {
+// CHECK: %call = call i64{{.*}}, !dbg [[G1R3:!.*]]
+// CHECK: [[gep:%.*]] = getelementptr inbounds nuw %struct.Ptr, ptr %p, i32 0, i32 0
+// CHECK: [[i2p:%.*]] = inttoptr i64 %call to ptr, !dbg [[G1R2:!.*]]
+// CHECK: store ptr [[i2p]], ptr [[gep]], align 8, !dbg [[G1R1:!.*]]
+    Ptr p = getPtr();
+// CHECK: ret void, !dbg [[G2R1:!.*]]
+}
+
+// CHECK: [[G1R3]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 3)
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
diff --git a/clang/test/KeyInstructions/coerced-through-memory.c b/clang/test/KeyInstructions/coerced-through-memory.c
new file mode 100644
index 0000000000000..7bdef09b88f5a
--- /dev/null
+++ b/clang/test/KeyInstructions/coerced-through-memory.c
@@ -0,0 +1,26 @@
+// RUN: %clang -gkey-instructions -gno-column-info -x c++ %s -gmlt -S -emit-llvm -o - -target aarch64-windows-msvc \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -gno-column-info -x c %s -gmlt -S -emit-llvm -o - -target aarch64-windows-msvc \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+typedef struct {
+  short a;
+  int b;
+  short c;
+} S;
+
+S getS(void);
+
+void f() {
+// CHECK: %call = call [2 x i64] {{.*}}getS{{.*}}(), !dbg [[G1R2:!.*]]
+//// Note: The store to the tmp alloca isn't part of the atom.
+// CHECK: store [2 x i64] %call, ptr %tmp.coerce, align 8
+// CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %s, ptr align 8 %tmp.coerce, i64 12, i1 false), !dbg [[G1R1:!.*]]
+  S s = getS();
+// CHECK: ret void, !dbg [[G2R1:!.*]]
+}
+
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
diff --git a/clang/test/KeyInstructions/coerced.c b/clang/test/KeyInstructions/coerced.c
new file mode 100644
index 0000000000000..db570719689fd
--- /dev/null
+++ b/clang/test/KeyInstructions/coerced.c
@@ -0,0 +1,40 @@
+// RUN: %clang -gkey-instructions -gno-column-info -x c++ %s -gmlt -S -emit-llvm -o - -target x86_64-unknown-linux \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank --check-prefixes=CHECK,CHECK-CXX
+
+// RUN: %clang -gkey-instructions -gno-column-info -x c %s -gmlt -S -emit-llvm -o - -target x86_64-unknown-linux \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank --check-prefixes=CHECK,CHECK-C
+
+typedef struct {
+  void* a;
+  void* b;
+} Struct;
+Struct get();
+
+void test() {
+// CHECK: %1 = extractvalue { ptr, ptr } %call, 0, !dbg [[G1R2:!.*]]
+// CHECK: store ptr %1, ptr {{.*}}, !dbg [[G1R1:!.*]]
+// CHECK: %3 = extractvalue { ptr, ptr } %call, 1, !dbg [[G1R2]]
+// CHECK: store ptr %3, ptr {{.*}}, !dbg [[G1R1:!.*]]
+  Struct s = get();
+// CHECK: ret void, !dbg [[G2R1:!.*]]
+}
+
+typedef struct { int i; } Int;
+Int getInt(void);
+
+// CHECK-C: @test2
+// CHECK-CXX: @_Z5test2v
+void test2() {
+// CHECK: %call = call i32 @{{(_Z6)?}}getInt{{v?}}(), !dbg [[T2_G1R2:!.*]]
+// CHECK: [[gep:%.*]] = getelementptr inbounds nuw %struct.Int, ptr %i, i32 0, i32 0
+// CHECK: store i32 %call, ptr [[gep]]{{.*}}, !dbg [[T2_G1R1:!.*]]
+  Int i = getInt();
+// CHECK: ret void, !dbg [[T2_G2R1:!.*]]
+}
+
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
+// CHECK: [[T2_G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[T2_G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[T2_G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)

``````````

</details>


https://github.com/llvm/llvm-project/pull/134653


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