[PATCH] D74183: [IRGen] Add an alignment attribute to underaligned sret parameters

[Erik Pilkington via Phabricator via cfe-commits]

erik.pilkington created this revision.
erik.pilkington added reviewers: rjmccall, scanon.
Herald added subscribers: ributzka, dexonsmith, jkorous.
Without this, LLVM will assume the pointer has the type's alignment, which is 
undefined if the value is actually underaligned.

rdar://58316406


https://reviews.llvm.org/D74183

Files:
  clang/lib/CodeGen/CGCall.cpp
  clang/test/CodeGen/aligned-sret.c
  clang/test/CodeGen/arm-varargs.c
  clang/test/CodeGen/arm64-arguments.c
  clang/test/CodeGen/arm64_32.c
  clang/test/CodeGen/systemz-abi-vector.c


Index: clang/test/CodeGen/systemz-abi-vector.c
===================================================================
--- clang/test/CodeGen/systemz-abi-vector.c
+++ clang/test/CodeGen/systemz-abi-vector.c
@@ -71,7 +71,7 @@
 
 v32i8 pass_v32i8(v32i8 arg) { return arg; }
 // CHECK-LABEL: define void @pass_v32i8(<32 x i8>* noalias sret %{{.*}}, <32 x i8>* %0)
-// CHECK-VECTOR-LABEL: define void @pass_v32i8(<32 x i8>* noalias sret %{{.*}}, <32 x i8>* %0)
+// CHECK-VECTOR-LABEL: define void @pass_v32i8(<32 x i8>* noalias sret align 8 %{{.*}}, <32 x i8>* %0)
 
 v1i16 pass_v1i16(v1i16 arg) { return arg; }
 // CHECK-LABEL: define void @pass_v1i16(<1 x i16>* noalias sret %{{.*}}, <1 x i16>* %0)
@@ -168,7 +168,7 @@
 struct agg_v32i8 { v32i8 a; };
 struct agg_v32i8 pass_agg_v32i8(struct agg_v32i8 arg) { return arg; }
 // CHECK-LABEL: define void @pass_agg_v32i8(%struct.agg_v32i8* noalias sret %{{.*}}, %struct.agg_v32i8* %{{.*}})
-// CHECK-VECTOR-LABEL: define void @pass_agg_v32i8(%struct.agg_v32i8* noalias sret %{{.*}}, %struct.agg_v32i8* %{{.*}})
+// CHECK-VECTOR-LABEL: define void @pass_agg_v32i8(%struct.agg_v32i8* noalias sret align 8 %{{.*}}, %struct.agg_v32i8* %{{.*}})
 
 
 // Verify that the following are *not* vector-like aggregate types
@@ -379,7 +379,7 @@
 // CHECK: [[VA_ARG_ADDR:%[^ ]+]] = phi <32 x i8>** [ [[REG_ADDR]], %{{.*}} ], [ [[MEM_ADDR]], %{{.*}} ]
 // CHECK: [[INDIRECT_ARG:%[^ ]+]] = load <32 x i8>*, <32 x i8>** [[VA_ARG_ADDR]]
 // CHECK: ret void
-// CHECK-VECTOR-LABEL: define void @va_v32i8(<32 x i8>* noalias sret %{{.*}}, %struct.__va_list_tag* %{{.*}})
+// CHECK-VECTOR-LABEL: define void @va_v32i8(<32 x i8>* noalias sret align 8 %{{.*}}, %struct.__va_list_tag* %{{.*}})
 // CHECK-VECTOR: [[REG_COUNT_PTR:%[^ ]+]] = getelementptr inbounds %struct.__va_list_tag, %struct.__va_list_tag* %{{.*}}, i32 0, i32 0
 // CHECK-VECTOR: [[REG_COUNT:%[^ ]+]] = load i64, i64* [[REG_COUNT_PTR]]
 // CHECK-VECTOR: [[FITS_IN_REGS:%[^ ]+]] = icmp ult i64 [[REG_COUNT]], 5
@@ -576,7 +576,7 @@
 // CHECK: [[VA_ARG_ADDR:%[^ ]+]] = phi %struct.agg_v32i8** [ [[REG_ADDR]], %{{.*}} ], [ [[MEM_ADDR]], %{{.*}} ]
 // CHECK: [[INDIRECT_ARG:%[^ ]+]] = load %struct.agg_v32i8*, %struct.agg_v32i8** [[VA_ARG_ADDR]]
 // CHECK: ret void
-// CHECK-VECTOR-LABEL: define void @va_agg_v32i8(%struct.agg_v32i8* noalias sret %{{.*}}, %struct.__va_list_tag* %{{.*}})
+// CHECK-VECTOR-LABEL: define void @va_agg_v32i8(%struct.agg_v32i8* noalias sret align 8 %{{.*}}, %struct.__va_list_tag* %{{.*}})
 // CHECK-VECTOR: [[REG_COUNT_PTR:%[^ ]+]] = getelementptr inbounds %struct.__va_list_tag, %struct.__va_list_tag* %{{.*}}, i32 0, i32 0
 // CHECK-VECTOR: [[REG_COUNT:%[^ ]+]] = load i64, i64* [[REG_COUNT_PTR]]
 // CHECK-VECTOR: [[FITS_IN_REGS:%[^ ]+]] = icmp ult i64 [[REG_COUNT]], 5
Index: clang/test/CodeGen/arm64_32.c
===================================================================
--- clang/test/CodeGen/arm64_32.c
+++ clang/test/CodeGen/arm64_32.c
@@ -27,4 +27,4 @@
 
 typedef float __attribute__((ext_vector_type(16))) v16f32;
 v16f32 func(v16f32 in) { return in; }
-// CHECK: define void @func(<16 x float>* noalias sret {{%.*}}, <16 x float> {{%.*}})
+// CHECK: define void @func(<16 x float>* noalias sret align 16 {{%.*}}, <16 x float> {{%.*}})
Index: clang/test/CodeGen/arm64-arguments.c
===================================================================
--- clang/test/CodeGen/arm64-arguments.c
+++ clang/test/CodeGen/arm64-arguments.c
@@ -181,9 +181,9 @@
 // CHECK: define <4 x float> @f1_1(<4 x float> %{{.*}})
 T_float32x4 f1_1(T_float32x4 a0) { return a0; }
 // Vector with length bigger than 16-byte is illegal and is passed indirectly.
-// CHECK: define void @f1_2(<8 x float>* noalias sret  %{{.*}}, <8 x float>* %0)
+// CHECK: define void @f1_2(<8 x float>* noalias sret align 16 %{{.*}}, <8 x float>* %0)
 T_float32x8 f1_2(T_float32x8 a0) { return a0; }
-// CHECK: define void @f1_3(<16 x float>* noalias sret %{{.*}}, <16 x float>* %0)
+// CHECK: define void @f1_3(<16 x float>* noalias sret align 16 %{{.*}}, <16 x float>* %0)
 T_float32x16 f1_3(T_float32x16 a0) { return a0; }
 
 // Testing alignment with aggregates: HFA, aggregates with size <= 16 bytes and
Index: clang/test/CodeGen/arm-varargs.c
===================================================================
--- clang/test/CodeGen/arm-varargs.c
+++ clang/test/CodeGen/arm-varargs.c
@@ -201,7 +201,7 @@
   long long val;
 } underaligned_long_long_struct;
 underaligned_long_long_struct underaligned_long_long_struct_test() {
-// CHECK-LABEL: define void @underaligned_long_long_struct_test(%struct.underaligned_long_long_struct* noalias sret %agg.result)
+// CHECK-LABEL: define void @underaligned_long_long_struct_test(%struct.underaligned_long_long_struct* noalias sret align 2 %agg.result)
   return va_arg(the_list, underaligned_long_long_struct);
 // CHECK: [[CUR:%[a-z0-9._]+]] = load i8*, i8** getelementptr inbounds (%struct.__va_list, %struct.__va_list* @the_list, i32 0, i32 0), align 4
 // CHECK: [[NEXT:%[a-z0-9._]+]] = getelementptr inbounds i8, i8* [[CUR]], i32 8
@@ -279,7 +279,7 @@
   long long val __attribute__((packed,aligned(2)));
 } underaligned_long_long_struct_member;
 underaligned_long_long_struct_member underaligned_long_long_struct_member_test() {
-// CHECK-LABEL: define void @underaligned_long_long_struct_member_test(%struct.underaligned_long_long_struct_member* noalias sret %agg.result)
+// CHECK-LABEL: define void @underaligned_long_long_struct_member_test(%struct.underaligned_long_long_struct_member* noalias sret align 2 %agg.result)
   return va_arg(the_list, underaligned_long_long_struct_member);
 // CHECK: [[CUR:%[a-z0-9._]+]] = load i8*, i8** getelementptr inbounds (%struct.__va_list, %struct.__va_list* @the_list, i32 0, i32 0), align 4
 // CHECK: [[NEXT:%[a-z0-9._]+]] = getelementptr inbounds i8, i8* [[CUR]], i32 8
Index: clang/test/CodeGen/aligned-sret.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/aligned-sret.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macos %s -S -emit-llvm -o- | FileCheck %s
+
+typedef __attribute__((__ext_vector_type__(4),__aligned__(16))) double simd_double4;
+typedef struct { simd_double4 columns[4]; } simd_double4x4;
+typedef simd_double4x4 matrix_double4x4;
+
+// CHECK: define void @ident(%struct.simd_double4x4* noalias sret align 16 %agg.result
+matrix_double4x4 ident(matrix_double4x4 x) {
+  return x;
+}
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -2071,6 +2071,10 @@
     hasUsedSRet = true;
     if (RetAI.getInReg())
       SRETAttrs.addAttribute(llvm::Attribute::InReg);
+    unsigned Align = RetAI.getIndirectAlign().getQuantity();
+    if (Align <
+        getDataLayout().getABITypeAlignment(getTypes().ConvertType(RetTy)))
+      SRETAttrs.addAlignmentAttr(Align);
     ArgAttrs[IRFunctionArgs.getSRetArgNo()] =
         llvm::AttributeSet::get(getLLVMContext(), SRETAttrs);
   }

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