Emit ASM input in a constant context
Summary:
Some ASM input constraints (e.g., "i" and "n") require immediate values. At O0,
very few code transformations are performed. So if we cannot resolve to an
immediate when emitting the ASM input we shouldn't delay its processing.
Reviewers: rsmith, efriedma
Reviewed By: efriedma
Subscribers: rehana, efriedma, craig.topper, jyknight, cfe-commits
Differential Revision: https://reviews.llvm.org/D55616
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index 7b69cb0..269fad3 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -685,7 +685,9 @@
// FIXME: Fail if % is used with the last operand.
break;
case 'i': // immediate integer.
+ break;
case 'n': // immediate integer with a known value.
+ Info.setRequiresImmediate();
break;
case 'I': // Various constant constraints with target-specific meanings.
case 'J':
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index bc7a18a..0242b48 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -1820,11 +1820,14 @@
// If this can't be a register or memory, i.e., has to be a constant
// (immediate or symbolic), try to emit it as such.
if (!Info.allowsRegister() && !Info.allowsMemory()) {
+ if (Info.requiresImmediateConstant()) {
+ llvm::APSInt AsmConst = InputExpr->EvaluateKnownConstInt(getContext());
+ return llvm::ConstantInt::get(getLLVMContext(), AsmConst);
+ }
+
Expr::EvalResult Result;
if (InputExpr->EvaluateAsInt(Result, getContext()))
return llvm::ConstantInt::get(getLLVMContext(), Result.Val.getInt());
- assert(!Info.requiresImmediateConstant() &&
- "Required-immediate inlineasm arg isn't constant?");
}
if (Info.allowsRegister() || !Info.allowsMemory())
diff --git a/clang/lib/Sema/SemaStmtAsm.cpp b/clang/lib/Sema/SemaStmtAsm.cpp
index d209266..b10b3d8 100644
--- a/clang/lib/Sema/SemaStmtAsm.cpp
+++ b/clang/lib/Sema/SemaStmtAsm.cpp
@@ -378,17 +378,17 @@
<< InputExpr->getSourceRange());
} else if (Info.requiresImmediateConstant() && !Info.allowsRegister()) {
if (!InputExpr->isValueDependent()) {
- Expr::EvalResult EVResult;
- if (!InputExpr->EvaluateAsInt(EVResult, Context))
+ llvm::SmallVector<PartialDiagnosticAt, 1> Diags;
+ llvm::APSInt Result = InputExpr->EvaluateKnownConstInt(Context, &Diags);
+ if (!Diags.empty())
return StmtError(
Diag(InputExpr->getBeginLoc(), diag::err_asm_immediate_expected)
<< Info.getConstraintStr() << InputExpr->getSourceRange());
- llvm::APSInt Result = EVResult.Val.getInt();
- if (!Info.isValidAsmImmediate(Result))
- return StmtError(Diag(InputExpr->getBeginLoc(),
- diag::err_invalid_asm_value_for_constraint)
- << Result.toString(10) << Info.getConstraintStr()
- << InputExpr->getSourceRange());
+ if (!Info.isValidAsmImmediate(Result))
+ return StmtError(Diag(InputExpr->getBeginLoc(),
+ diag::err_invalid_asm_value_for_constraint)
+ << Result.toString(10) << Info.getConstraintStr()
+ << InputExpr->getSourceRange());
}
} else {
diff --git a/clang/test/CodeGen/builtin-constant-p.c b/clang/test/CodeGen/builtin-constant-p.c
index 7f4e7d0..f1cd06a 100644
--- a/clang/test/CodeGen/builtin-constant-p.c
+++ b/clang/test/CodeGen/builtin-constant-p.c
@@ -1,4 +1,5 @@
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -O2 | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -O0 | FileCheck --check-prefix=O0 %s
int a = 42;
@@ -166,3 +167,13 @@
extern char test16_v;
struct { int a; } test16 = { __builtin_constant_p(test16_v) };
+
+extern unsigned long long test17_v;
+
+void test17() {
+ // O0: define void @test17
+ // O0: call void asm sideeffect "", {{.*}}(i32 -1)
+ // CHECK: define void @test17
+ // CHECK: call void asm sideeffect "", {{.*}}(i32 -1)
+ __asm__ __volatile__("" :: "n"( (__builtin_constant_p(test17_v) || 0) ? 1 : -1));
+}
