hans created this revision.
hans added reviewers: efriedma, rnk, rsmith, void.
Herald added subscribers: jdoerfert, eraman.
Apparently GCC allows this, and there's code relying on it (see bug, which is a
release blocker for llvm 8).
The idea is to allow expression that would have been allowed if they were cast
to int. So I based the code on how such a cast would be done (the
CK_PointerToIntegral case in IntExprEvaluator::VisitCastExpr()).
I'm unfamiliar with this code, especially the LValue variant of APValue, so
please take a careful look.
https://reviews.llvm.org/D58821
Files:
clang/lib/CodeGen/CGStmt.cpp
clang/lib/Sema/SemaStmtAsm.cpp
clang/test/CodeGen/x86-64-inline-asm.c
clang/test/Sema/inline-asm-validate-x86.c
Index: clang/test/Sema/inline-asm-validate-x86.c
===================================================================
--- clang/test/Sema/inline-asm-validate-x86.c
+++ clang/test/Sema/inline-asm-validate-x86.c
@@ -137,3 +137,15 @@
: "0"(i), "O"(64)); // expected-no-error
}
+void pr40890(void) {
+ struct s {
+ int a, b;
+ };
+ static struct s s;
+ // This null pointer can be used as an integer constant expression.
+ __asm__ __volatile__("\n#define S_A abcd%0\n" : : "n"(&((struct s*)0)->a));
+ // This offset-from-null pointer can be used as an integer constant expression.
+ __asm__ __volatile__("\n#define S_B abcd%0\n" : : "n"(&((struct s*)0)->b));
+ // This pointer cannot be used as an integer constant expression.
+ __asm__ __volatile__("\n#define GLOBAL_A abcd%0\n" : : "n"(&s.a)); // expected-error{{constraint 'n' expects an integer constant expression}}
+}
Index: clang/test/CodeGen/x86-64-inline-asm.c
===================================================================
--- clang/test/CodeGen/x86-64-inline-asm.c
+++ clang/test/CodeGen/x86-64-inline-asm.c
@@ -1,6 +1,7 @@
// REQUIRES: x86-registered-target
// RUN: %clang_cc1 -triple x86_64 %s -S -o /dev/null -DWARN -verify
// RUN: %clang_cc1 -triple x86_64 %s -S -o /dev/null -Werror -verify
+// RUN: %clang_cc1 -triple x86_64-linux-gnu %s -S -o - | FileCheck %s
void f() {
asm("movaps %xmm3, (%esi, 2)");
// expected-note@1 {{instantiated into assembly here}}
@@ -15,3 +16,15 @@
void g(void) { asm volatile("movd %%xmm0, %0"
:
: "m"(var)); }
+
+void pr40890(void) {
+ struct s {
+ int a, b;
+ } s;
+ __asm__ __volatile__("\n#define S_A abcd%0\n" : : "n"(&((struct s*)0)->a));
+ __asm__ __volatile__("\n#define S_B abcd%0\n" : : "n"(&((struct s*)0)->b));
+
+// CHECK-LABEL: pr40890
+// CHECK: #define S_A abcd$0
+// CHECK: #define S_B abcd$4
+}
Index: clang/lib/Sema/SemaStmtAsm.cpp
===================================================================
--- clang/lib/Sema/SemaStmtAsm.cpp
+++ clang/lib/Sema/SemaStmtAsm.cpp
@@ -385,11 +385,27 @@
return StmtError(
Diag(InputExpr->getBeginLoc(), diag::err_asm_immediate_expected)
<< Info.getConstraintStr() << InputExpr->getSourceRange());
- llvm::APSInt Result = EVResult.Val.getInt();
- if (!Info.isValidAsmImmediate(Result))
+
+ // For compatibility with GCC, we also allows pointers that would be
+ // integral constant expressions if they were cast to int.
+ llvm::APSInt IntResult;
+ if (EVResult.Val.isInt())
+ IntResult = EVResult.Val.getInt();
+ else if (EVResult.Val.isNullPointer())
+ IntResult = llvm::APSInt::get(
+ Context.getTargetNullPointerValue(InputExpr->getType()));
+ else if (EVResult.Val.isLValue() && !EVResult.Val.getLValueBase())
+ IntResult =
+ llvm::APSInt::get(EVResult.Val.getLValueOffset().getQuantity());
+ else
+ return StmtError(
+ Diag(InputExpr->getBeginLoc(), diag::err_asm_immediate_expected)
+ << Info.getConstraintStr() << InputExpr->getSourceRange());
+
+ if (!Info.isValidAsmImmediate(IntResult))
return StmtError(Diag(InputExpr->getBeginLoc(),
diag::err_invalid_asm_value_for_constraint)
- << Result.toString(10) << Info.getConstraintStr()
+ << IntResult.toString(10) << Info.getConstraintStr()
<< InputExpr->getSourceRange());
}
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -1838,8 +1838,22 @@
// (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 EVResult;
+ InputExpr->EvaluateAsRValue(EVResult, getContext(), true);
+
+ llvm::APSInt IntResult;
+ if (EVResult.Val.isInt())
+ IntResult = EVResult.Val.getInt();
+ else if (EVResult.Val.isNullPointer())
+ IntResult = llvm::APSInt::get(
+ getContext().getTargetNullPointerValue(InputExpr->getType()));
+ else if (EVResult.Val.isLValue() && !EVResult.Val.getLValueBase())
+ IntResult =
+ llvm::APSInt::get(EVResult.Val.getLValueOffset().getQuantity());
+ else
+ llvm_unreachable("Failed evaluate InputExpr as integer.");
+
+ return llvm::ConstantInt::get(getLLVMContext(), IntResult);
}
Expr::EvalResult Result;
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