Add support for declaring register contraints in variables. They are only used

in asm statements:

register int foo asm("rdi");

asm("..." : ... "r" (foo) ...

We also only accept these variables if the constraint in the asm statement is "r".

This fixes most of PR3933.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122643 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index 2c54332185b85e37339535b5c7789cedd99033cd..77984b11cca97cf5784a45bfdf94ca2db3e79b31 100644 (file)
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -104,9 +104,6 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
 /// EmitVarDecl - This method handles emission of any variable declaration
 /// inside a function, including static vars etc.
 void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
-  if (D.hasAttr<AsmLabelAttr>())
-    CGM.ErrorUnsupported(&D, "__asm__");
-
   switch (D.getStorageClass()) {
   case SC_None:
   case SC_Auto:

diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 098fe7f422479b06abfec88ce3f48137d2e097c5..1fcafe82e637c3f2a07ad4089c0d1993f07c4019 100644 (file)
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -919,6 +919,32 @@ SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
   return Result;
 }
 
+static std::string
+AddVariableConstraits(const std::string &Constraint, const Expr &AsmExpr,
+                      const TargetInfo &Target, CodeGenModule &CGM,
+                      const AsmStmt &Stmt) {
+  const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
+  if (!AsmDeclRef)
+    return Constraint;
+  const ValueDecl &Value = *AsmDeclRef->getDecl();
+  const VarDecl *Variable = dyn_cast<VarDecl>(&Value);
+  if (!Variable)
+    return Constraint;
+  AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>();
+  if (!Attr)
+    return Constraint;
+  llvm::StringRef Register = Attr->getLabel();
+  if (!Target.isValidGCCRegisterName(Register)) {
+    CGM.ErrorUnsupported(Variable, "__asm__");
+    return Constraint;
+  }
+  if (Constraint != "r") {
+    CGM.ErrorUnsupported(&Stmt, "__asm__");
+    return Constraint;
+  }
+  return "{" + Register.str() + "}";
+}
+
 llvm::Value*
 CodeGenFunction::EmitAsmInputLValue(const AsmStmt &S,
                                     const TargetInfo::ConstraintInfo &Info,
@@ -1056,6 +1082,9 @@ void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
     const Expr *OutExpr = S.getOutputExpr(i);
     OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());
 
+    OutputConstraint = AddVariableConstraits(OutputConstraint, *OutExpr, Target,
+                                             CGM, S);
+
     LValue Dest = EmitLValue(OutExpr);
     if (!Constraints.empty())
       Constraints += ',';
@@ -1133,6 +1162,11 @@ void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
     InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target,
                                          &OutputConstraintInfos);
 
+    InputConstraint =
+      AddVariableConstraits(InputConstraint,
+                            *InputExpr->IgnoreParenNoopCasts(getContext()),
+                            Target, CGM, S);
+
     llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints);
 
     // If this input argument is tied to a larger output result, extend the

diff --git a/test/CodeGen/asm-variable.c b/test/CodeGen/asm-variable.c
new file mode 100644 (file)
index 0000000..7f74913
--- /dev/null
+++ b/test/CodeGen/asm-variable.c
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm %s -o - | FileCheck %s
+
+unsigned long long foo(unsigned long long addr, unsigned long long a0,
+                       unsigned long long a1, unsigned long long a2,
+                       unsigned long long a3, unsigned long long a4,
+                       unsigned long long a5) {
+  register unsigned long long result asm("rax");
+  register unsigned long long b0 asm("rdi");
+  register unsigned long long b1 asm("rsi");
+  register unsigned long long b2 asm("rdx");
+  register unsigned long long b3 asm("rcx");
+  register unsigned long long b4 asm("r8");
+  register unsigned long long b5 asm("r9");
+
+  b0 = a0;
+  b1 = a1;
+  b2 = a2;
+  b3 = a3;
+  b4 = a4;
+  b5 = a5;
+
+  asm("call *%1" : "=r" (result)
+      : "r"(addr), "r" (b0), "r" (b1), "r" (b2), "r" (b3), "r" (b4), "r" (b5));
+  return result;
+}
+
+// CHECK: call i64 asm "call *$1", "={rax},r,{rdi},{rsi},{rdx},{rcx},{r8},{r9},~{dirflag},~{fpsr},~{flags}"