jyknight created this revision.
jyknight added a reviewer: majnemer.
jyknight added a subscriber: cfe-commits.
This is important in the case that the LLVM-inferred llvm-struct
alignment is not the same as the clang-known C-struct alignment.
http://reviews.llvm.org/D12243
Files:
lib/CodeGen/CGCall.cpp
test/CodeGen/le32-arguments.c
test/CodeGen/nvptx-abi.c
test/CodeGen/sparc-arguments.c
Index: test/CodeGen/sparc-arguments.c
===================================================================
--- /dev/null
+++ test/CodeGen/sparc-arguments.c
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -triple sparc-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+
+// Ensure that we pass proper alignment to llvm in the call
+// instruction. The proper alignment for the type is sometimes known
+// only by clang, and is not manifest in the LLVM-type. So, it must be
+// explicitly passed through. (Besides the case of the user specifying
+// alignment, as here, this situation also occurrs for non-POD C++
+// structs with tail-padding: clang emits those as packed llvm-structs
+// for some reason.)
+struct s1 {
+ long x;
+ char y;
+ int z;
+} __attribute__((packed, aligned(8)));
+
+struct s1 x1;
+
+void f1_helper(struct s1);
+// CHECK-LABEL: define void @f1()
+// CHECK: call void @f1_helper(%struct.s1* byval align 8 @x1)
+void f1() {
+ f1_helper(x1);
+}
Index: test/CodeGen/nvptx-abi.c
===================================================================
--- test/CodeGen/nvptx-abi.c
+++ test/CodeGen/nvptx-abi.c
@@ -21,14 +21,14 @@
void foo(float4_t x) {
// CHECK-LABEL: @foo
-// CHECK: %struct.float4_s* byval %x
+// CHECK: %struct.float4_s* byval align 4 %x
}
void fooN(float4_t x, float4_t y, float4_t z) {
// CHECK-LABEL: @fooN
-// CHECK: %struct.float4_s* byval %x
-// CHECK: %struct.float4_s* byval %y
-// CHECK: %struct.float4_s* byval %z
+// CHECK: %struct.float4_s* byval align 4 %x
+// CHECK: %struct.float4_s* byval align 4 %y
+// CHECK: %struct.float4_s* byval align 4 %z
}
typedef struct nested_s {
@@ -39,5 +39,5 @@
void baz(nested_t x) {
// CHECK-LABEL: @baz
-// CHECK: %struct.nested_s* byval %x)
+// CHECK: %struct.nested_s* byval align 8 %x)
}
Index: test/CodeGen/le32-arguments.c
===================================================================
--- test/CodeGen/le32-arguments.c
+++ test/CodeGen/le32-arguments.c
@@ -10,7 +10,7 @@
int bb;
} s1;
// Structs should be passed byval and not split up
-// CHECK-LABEL: define void @f1(%struct.s1* byval %i)
+// CHECK-LABEL: define void @f1(%struct.s1* byval align 4 %i)
void f1(s1 i) {}
typedef struct {
@@ -48,14 +48,14 @@
char b;
};
// Unions should be passed as byval structs
-// CHECK-LABEL: define void @f7(%union.simple_union* byval %s)
+// CHECK-LABEL: define void @f7(%union.simple_union* byval align 4 %s)
void f7(union simple_union s) {}
typedef struct {
int b4 : 4;
int b3 : 3;
int b8 : 8;
} bitfield1;
// Bitfields should be passed as byval structs
-// CHECK-LABEL: define void @f8(%struct.bitfield1* byval %bf1)
+// CHECK-LABEL: define void @f8(%struct.bitfield1* byval align 4 %bf1)
void f8(bitfield1 bf1) {}
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ lib/CodeGen/CGCall.cpp
@@ -1663,20 +1663,35 @@
Attrs.addAttribute(llvm::Attribute::InReg);
break;
- case ABIArgInfo::Indirect:
+ case ABIArgInfo::Indirect: {
if (AI.getInReg())
Attrs.addAttribute(llvm::Attribute::InReg);
if (AI.getIndirectByVal())
Attrs.addAttribute(llvm::Attribute::ByVal);
- Attrs.addAlignmentAttr(AI.getIndirectAlign());
+ unsigned Align = AI.getIndirectAlign();
+
+ // In a byval argument, it is important that the required
+ // alignment of the type is honored, as LLVM might be creating a
+ // *new* stack object, and needs to know what alignment to give
+ // it. (Sometimes it can deduce a sensible alignment on its own,
+ // but not if clang decides it must emit a packed struct, or the
+ // user specifies increased alignment requirements.)
+ //
+ // This is different from indirect *not* byval, where the object
+ // exists already, and the align attribute is purely
+ // informative.
+ if (Align == 0 && AI.getIndirectByVal())
+ Align = getContext().getTypeAlignInChars(ParamType).getQuantity();
+
+ Attrs.addAlignmentAttr(Align);
// byval disables readnone and readonly.
FuncAttrs.removeAttribute(llvm::Attribute::ReadOnly)
.removeAttribute(llvm::Attribute::ReadNone);
break;
-
+ }
case ABIArgInfo::Ignore:
case ABIArgInfo::Expand:
continue;
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
