Hi All,
This patch is for PR1582. As recent discuss on that pr, the C++ FE doesn't
track the restrict qualifier in the function declaration at all. When
llvm-gcc handling CALL_EXPR and emiting callInst instruction, it can't get
the "NoAlias" attribute, and hence insert a BitCast in CallInst. This patch
is to eliminate this bitcast.
Testcase attached here also.
Index: llvm-convert.cpp
===================================================================
--- llvm-convert.cpp (revision 43895)
+++ llvm-convert.cpp (working copy)
@@ -2846,8 +2846,16 @@
// to:
// %tmp = call float @foo( )
// This commonly occurs due to C "implicit ..." semantics.
+ //
+ // Or
+ //
+ // call void bitcast (void (i32* noalias)* @foo to void (i32*)*)(i32* %x)
+ // to:
+ // call void @foo(i32* %x noalias)
+ // This occurs due to C++ FE doesn't track the restrict qualifier
+ // in the function declaration at all.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Callee)) {
- if (CallOperands.empty() && CE->getOpcode() == Instruction::BitCast) {
+ if (CE->getOpcode() == Instruction::BitCast) {
Constant *RealCallee = CE->getOperand(0);
assert(isa<PointerType>(RealCallee->getType()) &&
"Bitcast to ptr not from ptr?");
@@ -2858,8 +2866,20 @@
const FunctionType *ActualFT =
cast<FunctionType>(ActualPT->getElementType());
if (RealFT->getReturnType() == ActualFT->getReturnType() &&
- ActualFT->getNumParams() == 0)
+ ActualFT->getNumParams() == 0 && CallOperands.empty())
Callee = RealCallee;
+ else if (RealFT->getReturnType() == ActualFT->getReturnType() &&
+ RealFT->getNumParams() == ActualFT->getNumParams() &&
+ RealFT->getNumParams() == CallOperands.size()) {
+ bool isSame = true;
+ for (unsigned i = 0; i < RealFT->getNumParams(); ++i)
+ if (RealFT->getParamType(i) != ActualFT->getParamType(i)) {
+ isSame = false;
+ break;
+ }
+ if (isSame)
+ Callee = RealCallee;
+ }
}
}
}
// RUN: %llvmgxx -c -emit-llvm %s -o - | llvm-dis | grep call | not grep bitcast
void foo(int * __restrict myptr1, int * myptr2) {
myptr1[0] = 0;
myptr2[0] = 0;
}
int main() {
int x, y;
foo(&x, &y);
return 0;
}
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