[inline-asm]No error for conflict between inputs\outputs and clobber list
According to extended asm syntax, a case where the clobber list includes a variable from the inputs or outputs should be an error - conflict.
for example:
const long double a = 0.0;
int main()
{
char b;
double t1 = a;
__asm__ ("fucompp": "=a" (b) : "u" (t1), "t" (t1) : "cc", "st", "st(1)");
return 0;
}
This should conflict with the output - t1 which is st, and st which is st aswell.
The patch fixes it.
Commit on behald of Ziv Izhar.
Differential Revision: https://reviews.llvm.org/D15075
llvm-svn: 290539
diff --git a/clang/lib/Sema/SemaStmtAsm.cpp b/clang/lib/Sema/SemaStmtAsm.cpp
index 9a18244..5036622 100644
--- a/clang/lib/Sema/SemaStmtAsm.cpp
+++ b/clang/lib/Sema/SemaStmtAsm.cpp
@@ -22,6 +22,7 @@
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringSet.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
using namespace clang;
using namespace sema;
@@ -137,6 +138,57 @@
return false;
}
+// Extracting the register name from the Expression value,
+// if there is no register name to extract, returns ""
+static StringRef extractRegisterName(const Expr *Expression,
+ const TargetInfo &Target) {
+ Expression = Expression->IgnoreImpCasts();
+ if (const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(Expression)) {
+ // Handle cases where the expression is a variable
+ const VarDecl *Variable = dyn_cast<VarDecl>(AsmDeclRef->getDecl());
+ if (Variable && Variable->getStorageClass() == SC_Register) {
+ if (AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>())
+ if (Target.isValidGCCRegisterName(Attr->getLabel()))
+ return Target.getNormalizedGCCRegisterName(Attr->getLabel(), true);
+ }
+ }
+ return "";
+}
+
+// Checks if there is a conflict between the input and output lists with the
+// clobbers list. If there's a conflict, returns the location of the
+// conflicted clobber, else returns nullptr
+static SourceLocation
+getClobberConflictLocation(MultiExprArg Exprs, StringLiteral **Constraints,
+ StringLiteral **Clobbers, int NumClobbers,
+ const TargetInfo &Target, ASTContext &Cont) {
+ llvm::StringSet<> InOutVars;
+ // Collect all the input and output registers from the extended asm
+ // statement
+ // in order to check for conflicts with the clobber list
+ for (int i = 0; i < Exprs.size(); ++i) {
+ StringRef Constraint = Constraints[i]->getString();
+ StringRef InOutReg = Target.getConstraintRegister(
+ Constraint, extractRegisterName(Exprs[i], Target));
+ if (InOutReg != "")
+ InOutVars.insert(InOutReg);
+ }
+ // Check for each item in the clobber list if it conflicts with the input
+ // or output
+ for (int i = 0; i < NumClobbers; ++i) {
+ StringRef Clobber = Clobbers[i]->getString();
+ // We only check registers, therefore we don't check cc and memory
+ // clobbers
+ if (Clobber == "cc" || Clobber == "memory")
+ continue;
+ Clobber = Target.getNormalizedGCCRegisterName(Clobber, true);
+ // Go over the output's registers we collected
+ if (InOutVars.count(Clobber))
+ return Clobbers[i]->getLocStart();
+ }
+ return SourceLocation();
+}
+
StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
bool IsVolatile, unsigned NumOutputs,
unsigned NumInputs, IdentifierInfo **Names,
@@ -543,6 +595,13 @@
return StmtError();
}
+ // Check for conflicts between clobber list and input or output lists
+ SourceLocation ConstraintLoc =
+ getClobberConflictLocation(Exprs, Constraints, Clobbers, NumClobbers,
+ Context.getTargetInfo(), Context);
+ if (ConstraintLoc.isValid())
+ return Diag(ConstraintLoc, diag::error_inoutput_conflict_with_clobber);
+
return NS;
}