Author: jyknight Date: Fri Aug 21 13:19:06 2015 New Revision: 245719 URL: http://llvm.org/viewvc/llvm-project?rev=245719&view=rev Log: Properly provide alignment of 'byval' arguments down to llvm.
This is important in the case that the LLVM-inferred llvm-struct alignment is not the same as the clang-known C-struct alignment. Differential Revision: http://reviews.llvm.org/D12243 Added: cfe/trunk/test/CodeGen/sparc-arguments.c Modified: cfe/trunk/lib/CodeGen/CGCall.cpp cfe/trunk/test/CodeGen/le32-arguments.c cfe/trunk/test/CodeGen/nvptx-abi.c Modified: cfe/trunk/lib/CodeGen/CGCall.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=245719&r1=245718&r2=245719&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CGCall.cpp (original) +++ cfe/trunk/lib/CodeGen/CGCall.cpp Fri Aug 21 13:19:06 2015 @@ -1663,20 +1663,35 @@ void CodeGenModule::ConstructAttributeLi 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; Modified: cfe/trunk/test/CodeGen/le32-arguments.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/le32-arguments.c?rev=245719&r1=245718&r2=245719&view=diff ============================================================================== --- cfe/trunk/test/CodeGen/le32-arguments.c (original) +++ cfe/trunk/test/CodeGen/le32-arguments.c Fri Aug 21 13:19:06 2015 @@ -10,7 +10,7 @@ typedef struct { 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 { @@ -48,7 +48,7 @@ union simple_union { 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 { @@ -57,5 +57,5 @@ typedef struct { 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) {} Modified: cfe/trunk/test/CodeGen/nvptx-abi.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/nvptx-abi.c?rev=245719&r1=245718&r2=245719&view=diff ============================================================================== --- cfe/trunk/test/CodeGen/nvptx-abi.c (original) +++ cfe/trunk/test/CodeGen/nvptx-abi.c Fri Aug 21 13:19:06 2015 @@ -21,14 +21,14 @@ float bar(void) { 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 @@ typedef struct nested_s { void baz(nested_t x) { // CHECK-LABEL: @baz -// CHECK: %struct.nested_s* byval %x) +// CHECK: %struct.nested_s* byval align 8 %x) } Added: cfe/trunk/test/CodeGen/sparc-arguments.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/sparc-arguments.c?rev=245719&view=auto ============================================================================== --- cfe/trunk/test/CodeGen/sparc-arguments.c (added) +++ cfe/trunk/test/CodeGen/sparc-arguments.c Fri Aug 21 13:19:06 2015 @@ -0,0 +1,27 @@ +// 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 these as packed llvm-structs +// for ABI reasons.) + +struct s1 { + int x; +} __attribute__((aligned(8))); + +struct s1 x1; + + +// Ensure the align 8 is passed through: +// CHECK-LABEL: define void @f1() +// CHECK: call void @f1_helper(%struct.s1* byval align 8 @x1) +// Also ensure the declaration of f1_helper includes it +// CHECK: declare void @f1_helper(%struct.s1* byval align 8) + +void f1_helper(struct s1); +void f1() { + f1_helper(x1); +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
