[clang] b2bd024 - [CGExprAgg] Don't create zero index GEP

[Nikita Popov via cfe-commits]

Author: Nikita Popov
Date: 2024-05-30T11:47:07+02:00
New Revision: b2bd024384b484647da9fd9863bf6f77b5731949

URL: https://github.com/llvm/llvm-project/commit/b2bd024384b484647da9fd9863bf6f77b5731949
DIFF: https://github.com/llvm/llvm-project/commit/b2bd024384b484647da9fd9863bf6f77b5731949.diff

LOG: [CGExprAgg] Don't create zero index GEP

With opaque pointers, we no longer need a zero-index GEP to get
the first element.

Added: 
    

Modified: 
    clang/lib/CodeGen/CGExprAgg.cpp
    clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-startend.cpp
    clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 7a92fc3dfb4a4..5b2039af6128b 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -448,11 +448,7 @@ AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
   AggValueSlot Dest = EnsureSlot(E->getType());
   LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
   LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
-  llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
-  llvm::Value *IdxStart[] = { Zero, Zero };
-  llvm::Value *ArrayStart = Builder.CreateInBoundsGEP(
-      ArrayPtr.getElementType(), ArrayPtr.emitRawPointer(CGF), IdxStart,
-      "arraystart");
+  llvm::Value *ArrayStart = ArrayPtr.emitRawPointer(CGF);
   CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start);
   ++Field;
 
@@ -467,6 +463,7 @@ AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
       Ctx.hasSameType(Field->getType()->getPointeeType(),
                       ArrayType->getElementType())) {
     // End pointer.
+    llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
     llvm::Value *IdxEnd[] = { Zero, Size };
     llvm::Value *ArrayEnd = Builder.CreateInBoundsGEP(
         ArrayPtr.getElementType(), ArrayPtr.emitRawPointer(CGF), IdxEnd,

diff  --git a/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-startend.cpp b/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-startend.cpp
index a95a458220b08..d9e4c5d5403c2 100644
--- a/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-startend.cpp
+++ b/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-startend.cpp
@@ -49,7 +49,6 @@ void fn1(int i) {
   // CHECK-NEXT: store
   // init the list
   // CHECK-NEXT: getelementptr
-  // CHECK-NEXT: getelementptr inbounds [3 x i32], ptr
   // CHECK-NEXT: store ptr
   // CHECK-NEXT: getelementptr
   // CHECK-NEXT: getelementptr inbounds [3 x i32], ptr [[array]], i{{32|64}} 0, i{{32|64}} 3

diff  --git a/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp b/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp
index d97a9310cdcfa..aa2f078a5fb0c 100644
--- a/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp
+++ b/clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp
@@ -131,7 +131,6 @@ void fn1(int i) {
   // CHECK-NEXT: store
   // init the list
   // CHECK-NEXT: getelementptr
-  // CHECK-NEXT: getelementptr inbounds [3 x i32], ptr
   // CHECK-NEXT: store ptr
   // CHECK-NEXT: getelementptr
   // CHECK-NEXT: store i{{32|64}} 3