Clang changes for alloc_align attribute

GCC has the alloc_align attribute, which is similar to assume_aligned, except the attribute's parameter is the index of the integer parameter that needs aligning to.

Differential Revision: https://reviews.llvm.org/D29599

llvm-svn: 299117

2 files changed, 10 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 55191b223d0..e11bc94dd83 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -4348,6 +4348,10 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
       llvm::ConstantInt *AlignmentCI = cast<llvm::ConstantInt>(Alignment);
       EmitAlignmentAssumption(Ret.getScalarVal(), AlignmentCI->getZExtValue(),
                               OffsetValue);
+    } else if (const auto *AA = TargetDecl->getAttr<AllocAlignAttr>()) {
+      llvm::Value *ParamVal =
+          CallArgs[AA->getParamIndex() - 1].RV.getScalarVal();
+      EmitAlignmentAssumption(Ret.getScalarVal(), ParamVal);
     }
   }
 
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 4a7cc0253b4..ee85e30173e 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -2465,6 +2465,12 @@ public:
   PeepholeProtection protectFromPeepholes(RValue rvalue);
   void unprotectFromPeepholes(PeepholeProtection protection);
 
+  void EmitAlignmentAssumption(llvm::Value *PtrValue, llvm::Value *Alignment,
+                               llvm::Value *OffsetValue = nullptr) {
+    Builder.CreateAlignmentAssumption(CGM.getDataLayout(), PtrValue, Alignment,
+                                      OffsetValue);
+  }
+
   //===--------------------------------------------------------------------===//
   //                             Statement Emission
   //===--------------------------------------------------------------------===//