[llvm-branch-commits] CodeGen: Fix implementation of __builtin_trivially_relocate. (PR #140312)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Peter Collingbourne (pcc)

<details>
<summary>Changes</summary>

The builtin is documented to copy `count` elements, but the implementation
copies `count` bytes. Fix that.


---
Full diff: https://github.com/llvm/llvm-project/pull/140312.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CGBuiltin.cpp (+8) 
- (modified) clang/test/CodeGenCXX/cxx2c-trivially-relocatable.cpp (+1-1) 


``````````diff
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 48cfbda12b2ac..0cfb88a9d9789 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -4425,6 +4425,14 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     Address Dest = EmitPointerWithAlignment(E->getArg(0));
     Address Src = EmitPointerWithAlignment(E->getArg(1));
     Value *SizeVal = EmitScalarExpr(E->getArg(2));
+    if (BuiltinIDIfNoAsmLabel == Builtin::BI__builtin_trivially_relocate)
+      SizeVal = Builder.CreateMul(
+          SizeVal,
+          ConstantInt::get(
+              SizeVal->getType(),
+              getContext()
+                  .getTypeSizeInChars(E->getArg(0)->getType()->getPointeeType())
+                  .getQuantity()));
     EmitArgCheck(TCK_Store, Dest, E->getArg(0), 0);
     EmitArgCheck(TCK_Load, Src, E->getArg(1), 1);
     Builder.CreateMemMove(Dest, Src, SizeVal, false);
diff --git a/clang/test/CodeGenCXX/cxx2c-trivially-relocatable.cpp b/clang/test/CodeGenCXX/cxx2c-trivially-relocatable.cpp
index 17144cffb6476..63f3ba8e74ed5 100644
--- a/clang/test/CodeGenCXX/cxx2c-trivially-relocatable.cpp
+++ b/clang/test/CodeGenCXX/cxx2c-trivially-relocatable.cpp
@@ -8,7 +8,7 @@ struct S trivially_relocatable_if_eligible {
 };
 
 // CHECK: @_Z4testP1SS0_
-// CHECK: call void @llvm.memmove.p0.p0.i64
+// CHECK: call void @llvm.memmove.p0.p0.i64({{.*}}, i64 8
 // CHECK-NOT: __builtin
 // CHECK: ret
 void test(S* source, S* dest) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/140312