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Preserve early clobber flag when using named registers in inline assembly. 

Summary:
Named registers with the constraint "=&r" currently lose the early clobber flag
and turn into "=r" when converted to LLVM-IR. This patch correctly passes it on.

Reviewers: atanasyan

Reviewed By: atanasyan

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D7346

llvm-svn: 228143
This commit is contained in:
Daniel Sanders 2015-02-04 14:25:47 +00:00
parent 34c325e749
commit aa748a8db5
3 changed files with 30 additions and 5 deletions
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9
clang/lib/CodeGen/CGStmt.cpp
View File

@ -1696,7 +1696,7 @@ SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
static std::string
AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
const TargetInfo &Target, CodeGenModule &CGM,
const AsmStmt &Stmt) {
const AsmStmt &Stmt, const bool EarlyClobber) {
const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
if (!AsmDeclRef)
return Constraint;
@ -1721,7 +1721,7 @@ AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
}
// Canonicalize the register here before returning it.
Register = Target.getNormalizedGCCRegisterName(Register);
return "{" + Register.str() + "}";
return (EarlyClobber ? "&{" : "{") + Register.str() + "}";
}
llvm::Value*
@ -1854,7 +1854,8 @@ void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());
OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr,
getTarget(), CGM, S);
getTarget(), CGM, S,
Info.earlyClobber());
LValue Dest = EmitLValue(OutExpr);
if (!Constraints.empty())
@ -1959,7 +1960,7 @@ void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
InputConstraint =
AddVariableConstraints(InputConstraint,
*InputExpr->IgnoreParenNoopCasts(getContext()),
getTarget(), CGM, S);
getTarget(), CGM, S, Info.earlyClobber());
llvm::Value *Arg = EmitAsmInput(Info, InputExpr, Constraints);

2
clang/test/CodeGen/arm-asm-variable.c
View File

@ -17,7 +17,7 @@ int64_t foo(int64_t v, volatile int64_t *p)
: [_rl] "=&r" (rl), [_rh] "=&r" (rh) \
: [_p] "p" (p) : "memory");
// CHECK: call { i32, i32 } asm sideeffect "ldrexd$0, $1, [$2]", "={r1},={r2},r,~{memory}"(i64*
// CHECK: call { i32, i32 } asm sideeffect "ldrexd$0, $1, [$2]", "=&{r1},=&{r2},r,~{memory}"(i64*
return r;
}

24
clang/test/CodeGen/asm-reg-var-local.c
View File

@ -2,6 +2,7 @@
// Exercise various use cases for local asm "register variables".
int foo() {
// CHECK-LABEL: define i32 @foo()
// CHECK: [[A:%[a-zA-Z0-9]+]] = alloca i32
register int a asm("rsi")=5;
@ -22,3 +23,26 @@ int foo() {
// CHECK: [[TMP1:%[a-zA-Z0-9]+]] = load i32* [[A]]
// CHECK: ret i32 [[TMP1]]
}
int earlyclobber() {
// CHECK-LABEL: define i32 @earlyclobber()
// CHECK: [[A:%[a-zA-Z0-9]+]] = alloca i32
register int a asm("rsi")=5;
// CHECK: store i32 5, i32* [[A]]
asm volatile("; %0 This asm defines rsi" : "=&r"(a));
// CHECK: [[Z:%[a-zA-Z0-9]+]] = call i32 asm sideeffect "; $0 This asm defines rsi", "=&{rsi},~{dirflag},~{fpsr},~{flags}"()
// CHECK: store i32 [[Z]], i32* [[A]]
a = 42;
// CHECK: store i32 42, i32* [[A]]
asm volatile("; %0 This asm uses rsi" : : "r"(a));
// CHECK: [[TMP:%[a-zA-Z0-9]+]] = load i32* [[A]]
// CHECK: call void asm sideeffect "; $0 This asm uses rsi", "{rsi},~{dirflag},~{fpsr},~{flags}"(i32 [[TMP]])
return a;
// CHECK: [[TMP1:%[a-zA-Z0-9]+]] = load i32* [[A]]
// CHECK: ret i32 [[TMP1]]
}