PNaCl: Add ExpandByVal pass for expanding out by-value struct args and results

test/Transforms/NaCl/expand-byval.ll

+; RUN: opt -expand-byval %s -S | FileCheck %s
+
+target datalayout = "p:32:32:32"
+
+%MyStruct = type { i32, i8, i32 }
+%AlignedStruct = type { double, double }
+
+
+; Removal of "byval" attribute for passing structs arguments by value
+
+declare void @ext_func(%MyStruct*)
+
+define void @byval_receiver(%MyStruct* byval align 32 %ptr) {
+  call void @ext_func(%MyStruct* %ptr)
+  ret void
+}
+; Strip the "byval" and "align" attributes.
+; CHECK: define void @byval_receiver(%MyStruct* %ptr) {
+; CHECK-NEXT: call void @ext_func(%MyStruct* %ptr)
+
+
+declare void @ext_byval_func(%MyStruct* byval)
+; CHECK: declare void @ext_byval_func(%MyStruct*)
+
+define void @byval_caller(%MyStruct* %ptr) {
+  call void @ext_byval_func(%MyStruct* byval %ptr)
+  ret void
+}
+; CHECK: define void @byval_caller(%MyStruct* %ptr) {
+; CHECK-NEXT: %ptr.byval_copy = alloca %MyStruct, align 4
+; CHECK: call void @llvm.lifetime.start(i64 12, i8* %{{.*}})
+; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %{{.*}}, i8* %{{.*}}, i64 12, i32 0, i1 false)
+; CHECK-NEXT: call void @ext_byval_func(%MyStruct* %ptr.byval_copy)
+
+
+define void @byval_tail_caller(%MyStruct* %ptr) {
+  tail call void @ext_byval_func(%MyStruct* byval %ptr)
+  ret void
+}
+; CHECK: define void @byval_tail_caller(%MyStruct* %ptr) {
+; CHECK: {{^}} call void @ext_byval_func(%MyStruct* %ptr.byval_copy)
+
+
+define void @byval_invoke(%MyStruct* %ptr) {
+  invoke void @ext_byval_func(%MyStruct* byval align 32 %ptr)
+      to label %cont unwind label %lpad
+cont:
+  ret void
+lpad:
+  %lp = landingpad { i8*, i32 } personality i8* null cleanup
+  ret void
+}
+; CHECK: define void @byval_invoke(%MyStruct* %ptr) {
+; CHECK: %ptr.byval_copy = alloca %MyStruct, align 32
+; CHECK: call void @llvm.lifetime.start(i64 12, i8* %{{.*}})
+; CHECK: invoke void @ext_byval_func(%MyStruct* %ptr.byval_copy)
+; CHECK: cont:
+; CHECK: call void @llvm.lifetime.end(i64 12, i8* %{{.*}})
+; CHECK: lpad:
+; CHECK: call void @llvm.lifetime.end(i64 12, i8* %{{.*}})
+
+
+; Check handling of alignment
+
+; Check that "align" is stripped for declarations too.
+declare void @ext_byval_func_align(%MyStruct* byval align 32)
+; CHECK: declare void @ext_byval_func_align(%MyStruct*)
+
+define void @byval_caller_align_via_attr(%MyStruct* %ptr) {
+  call void @ext_byval_func(%MyStruct* byval align 32 %ptr)
+  ret void
+}
+; CHECK: define void @byval_caller_align_via_attr(%MyStruct* %ptr) {
+; CHECK-NEXT: %ptr.byval_copy = alloca %MyStruct, align 32
+; The memcpy may assume that %ptr is 32-byte-aligned.
+; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %2, i8* %3, i64 12, i32 32, i1 false)
+
+declare void @ext_byval_func_align_via_type(%AlignedStruct* byval)
+
+; %AlignedStruct contains a double so requires an alignment of 8 bytes.
+; Looking at the alignment of %AlignedStruct is a workaround for a bug
+; in pnacl-clang:
+; https://code.google.com/p/nativeclient/issues/detail?id=3403
+define void @byval_caller_align_via_type(%AlignedStruct* %ptr) {
+  call void @ext_byval_func_align_via_type(%AlignedStruct* byval %ptr)
+  ret void
+}
+; CHECK: define void @byval_caller_align_via_type(%AlignedStruct* %ptr) {
+; CHECK-NEXT: %ptr.byval_copy = alloca %AlignedStruct, align 8
+; Don't assume that %ptr is 8-byte-aligned when doing the memcpy.
+; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %{{.*}}, i8* %{{.*}}, i64 16, i32 0, i1 false)
+
+
+; Removal of "sret" attribute for returning structs by value
+
+declare void @ext_sret_func(%MyStruct* sret align 32)
+; CHECK: declare void @ext_sret_func(%MyStruct*)
+
+define void @sret_func(%MyStruct* sret align 32 %buf) {
+  ret void
+}
+; CHECK: define void @sret_func(%MyStruct* %buf) {
+
+define void @sret_caller(%MyStruct* %buf) {
+  call void @ext_sret_func(%MyStruct* sret align 32 %buf)
+  ret void
+}
+; CHECK: define void @sret_caller(%MyStruct* %buf) {
+; CHECK-NEXT: call void @ext_sret_func(%MyStruct* %buf)
+
+
+; Check that other attributes are preserved
+
+define void @inreg_attr(%MyStruct* inreg %ptr) {
+  ret void
+}
+; CHECK: define void @inreg_attr(%MyStruct* inreg %ptr) {
+
+declare void @func_attrs() #0
+; CHECK: declare void @func_attrs() #0
+
+attributes #0 = { noreturn nounwind }
+; CHECK: attributes #0 = { noreturn nounwind }