Implement SparcV9ABIInfo::EmitVAArg.

This could actually be implemented with the LLVM IR va_arg instruction,
but it doesn't seem to offer any advantages over accessing the va_list
pointer directly.

Using the va_list pointer directly makes it possible to perform type
coercion directly from the argument array, and the va_list updates are
exposed to the optimizers.

llvm-svn: 183292

2 files changed, 111 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 6e5084a1492..c4ee7246a5b 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -5332,8 +5332,52 @@ SparcV9ABIInfo::classifyType(QualType Ty, unsigned SizeLimit) const {
 
 llvm::Value *SparcV9ABIInfo::EmitVAArg(llvm::Value *VAListAddr, QualType Ty,
                                        CodeGenFunction &CGF) const {
-  // FIXME: Implement with va_arg.
-  return 0;
+  ABIArgInfo AI = classifyType(Ty, 16 * 8);
+  llvm::Type *ArgTy = CGT.ConvertType(Ty);
+  if (AI.canHaveCoerceToType() && !AI.getCoerceToType())
+    AI.setCoerceToType(ArgTy);
+
+  llvm::Type *BPP = CGF.Int8PtrPtrTy;
+  CGBuilderTy &Builder = CGF.Builder;
+  llvm::Value *VAListAddrAsBPP = Builder.CreateBitCast(VAListAddr, BPP, "ap");
+  llvm::Value *Addr = Builder.CreateLoad(VAListAddrAsBPP, "ap.cur");
+  llvm::Type *ArgPtrTy = llvm::PointerType::getUnqual(ArgTy);
+  llvm::Value *ArgAddr;
+  unsigned Stride;
+
+  switch (AI.getKind()) {
+  case ABIArgInfo::Expand:
+    llvm_unreachable("Unsupported ABI kind for va_arg");
+
+  case ABIArgInfo::Extend:
+    Stride = 8;
+    ArgAddr = Builder
+      .CreateConstGEP1_32(Addr, 8 - getDataLayout().getTypeAllocSize(ArgTy),
+                          "extend");
+    break;
+
+  case ABIArgInfo::Direct:
+    Stride = getDataLayout().getTypeAllocSize(AI.getCoerceToType());
+    ArgAddr = Addr;
+    break;
+
+  case ABIArgInfo::Indirect:
+    Stride = 8;
+    ArgAddr = Builder.CreateBitCast(Addr,
+                                    llvm::PointerType::getUnqual(ArgPtrTy),
+                                    "indirect");
+    ArgAddr = Builder.CreateLoad(ArgAddr, "indirect.arg");
+    break;
+
+  case ABIArgInfo::Ignore:
+    return llvm::UndefValue::get(ArgPtrTy);
+  }
+
+  // Update VAList.
+  Addr = Builder.CreateConstGEP1_32(Addr, Stride, "ap.next");
+  Builder.CreateStore(Addr, VAListAddrAsBPP);
+
+  return Builder.CreatePointerCast(ArgAddr, ArgPtrTy, "arg.addr");
 }
 
 void SparcV9ABIInfo::computeInfo(CGFunctionInfo &FI) const {
diff --git a/clang/test/CodeGen/sparcv9-abi.c b/clang/test/CodeGen/sparcv9-abi.c
index b58c84689ad..22803a6d4c4 100644
--- a/clang/test/CodeGen/sparcv9-abi.c
+++ b/clang/test/CodeGen/sparcv9-abi.c
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -triple sparcv9-unknown-linux -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple sparcv9-unknown-unknown -emit-llvm %s -o - | FileCheck %s
+#include <stdarg.h>
 
 // CHECK: define void @f_void()
 void f_void(void) {}
@@ -115,3 +116,66 @@ void call_tiny() {
   struct tiny x = { 1 };
   f_tiny(x);
 }
+
+// CHECK: define signext i32 @f_variable(i8* %f, ...)
+// CHECK: %ap = alloca i8*
+// CHECK: call void @llvm.va_start
+//
+int f_variable(char *f, ...) {
+  int s = 0;
+  char c;
+  va_list ap;
+  va_start(ap, f);
+  while ((c = *f++)) switch (c) {
+
+// CHECK: %[[CUR:[^ ]+]] = load i8** %ap
+// CHECK-DAG: %[[NXT:[^ ]+]] = getelementptr i8* %[[CUR]], i32 8
+// CHECK-DAG: store i8* %[[NXT]], i8** %ap
+// CHECK-DAG: %[[EXT:[^ ]+]] = getelementptr i8* %[[CUR]], i32 4
+// CHECK-DAG: %[[ADR:[^ ]+]] = bitcast i8* %[[EXT]] to i32*
+// CHECK-DAG: load i32* %[[ADR]]
+// CHECK: br
+  case 'i':
+    s += va_arg(ap, int);
+    break;
+
+// CHECK: %[[CUR:[^ ]+]] = load i8** %ap
+// CHECK-DAG: %[[NXT:[^ ]+]] = getelementptr i8* %[[CUR]], i32 8
+// CHECK-DAG: store i8* %[[NXT]], i8** %ap
+// CHECK-DAG: %[[ADR:[^ ]+]] = bitcast i8* %[[CUR]] to i64*
+// CHECK-DAG: load i64* %[[ADR]]
+// CHECK: br
+  case 'l':
+    s += va_arg(ap, long);
+    break;
+
+// CHECK: %[[CUR:[^ ]+]] = load i8** %ap
+// CHECK-DAG: %[[NXT:[^ ]+]] = getelementptr i8* %[[CUR]], i32 8
+// CHECK-DAG: store i8* %[[NXT]], i8** %ap
+// CHECK-DAG: %[[ADR:[^ ]+]] = bitcast i8* %[[CUR]] to %struct.tiny*
+// CHECK: br
+  case 't':
+    s += va_arg(ap, struct tiny).a;
+    break;
+
+// CHECK: %[[CUR:[^ ]+]] = load i8** %ap
+// CHECK-DAG: %[[NXT:[^ ]+]] = getelementptr i8* %[[CUR]], i32 16
+// CHECK-DAG: store i8* %[[NXT]], i8** %ap
+// CHECK-DAG: %[[ADR:[^ ]+]] = bitcast i8* %[[CUR]] to %struct.small*
+// CHECK: br
+  case 's':
+    s += *va_arg(ap, struct small).a;
+    break;
+
+// CHECK: %[[CUR:[^ ]+]] = load i8** %ap
+// CHECK-DAG: %[[NXT:[^ ]+]] = getelementptr i8* %[[CUR]], i32 8
+// CHECK-DAG: store i8* %[[NXT]], i8** %ap
+// CHECK-DAG: %[[IND:[^ ]+]] = bitcast i8* %[[CUR]] to %struct.medium**
+// CHECK-DAG: %[[ADR:[^ ]+]] = load %struct.medium** %[[IND]]
+// CHECK: br
+  case 'm':
+    s += *va_arg(ap, struct medium).a;
+    break;
+  }
+  return s;
+}