[clang] 91d415b - [Clang][AArch64][SVE] Allow write to SVE vector elements using the subscript operator (#91965)

[via cfe-commits]

Author: Momchil Velikov
Date: 2024-05-22T10:41:03+01:00
New Revision: 91d415b8d94b15023e6c39d5376274a2b21ee448

URL: https://github.com/llvm/llvm-project/commit/91d415b8d94b15023e6c39d5376274a2b21ee448
DIFF: https://github.com/llvm/llvm-project/commit/91d415b8d94b15023e6c39d5376274a2b21ee448.diff

LOG: [Clang][AArch64][SVE] Allow write to SVE vector elements using the subscript operator (#91965)

The patch at https://reviews.llvm.org/D122732 introduced using the array
subscript operator for SVE vectors, however it also causes an ICE when
the subscripting expression is used as an lvalue.

This patches fixes the error. Lvalue subscripting expressions are
emitted as LLVM IR `insertelement`.

Added: 
    

Modified: 
    clang/lib/CodeGen/CGExpr.cpp
    clang/lib/Sema/SemaExpr.cpp
    clang/test/CodeGen/aarch64-sve-vector-subscript-ops.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index cd1c48b420382..6f9237e2067f5 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -4180,7 +4180,7 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
 
   // If the base is a vector type, then we are forming a vector element lvalue
   // with this subscript.
-  if (E->getBase()->getType()->isVectorType() &&
+  if (E->getBase()->getType()->isSubscriptableVectorType() &&
       !isa<ExtVectorElementExpr>(E->getBase())) {
     // Emit the vector as an lvalue to get its address.
     LValue LHS = EmitLValue(E->getBase());

diff  --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index f0ad3de311387..282508d489a5e 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -5185,7 +5185,7 @@ Sema::CreateBuiltinArraySubscriptExpr(Expr *Base, SourceLocation LLoc,
   }
 
   // Perform default conversions.
-  if (!LHSExp->getType()->getAs<VectorType>()) {
+  if (!LHSExp->getType()->isSubscriptableVectorType()) {
     ExprResult Result = DefaultFunctionArrayLvalueConversion(LHSExp);
     if (Result.isInvalid())
       return ExprError();

diff  --git a/clang/test/CodeGen/aarch64-sve-vector-subscript-ops.c b/clang/test/CodeGen/aarch64-sve-vector-subscript-ops.c
index fb60c6d100ce6..52a05d010de9b 100644
--- a/clang/test/CodeGen/aarch64-sve-vector-subscript-ops.c
+++ b/clang/test/CodeGen/aarch64-sve-vector-subscript-ops.c
@@ -88,3 +88,25 @@ float subscript_float32(svfloat32_t a, size_t b) {
 double subscript_float64(svfloat64_t a, size_t b) {
   return a[b];
 }
+
+// CHECK-LABEL: @subscript_write_float32(
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[VECINS:%.*]] = insertelement <vscale x 4 x float> [[A:%.*]], float 1.000000e+00, i64 [[B:%.*]]
+// CHECK-NEXT:    ret <vscale x 4 x float> [[VECINS]]
+//
+svfloat32_t subscript_write_float32(svfloat32_t a, size_t b) {
+  a[b] = 1.0f;
+  return a;
+}
+
+// CHECK-LABEL: @subscript_read_write_float32(
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[VECEXT:%.*]] = extractelement <vscale x 4 x float> [[A:%.*]], i64 [[B:%.*]]
+// CHECK-NEXT:    [[ADD:%.*]] = fadd float [[VECEXT]], 1.000000e+00
+// CHECK-NEXT:    [[VECINS:%.*]] = insertelement <vscale x 4 x float> [[A]], float [[ADD]], i64 [[B]]
+// CHECK-NEXT:    ret <vscale x 4 x float> [[VECINS]]
+//
+svfloat32_t subscript_read_write_float32(svfloat32_t a, size_t b) {
+  a[b] += 1.0f;
+  return a;
+}