X86FastISel doesn't support the -tailcallopt ABI.

llvm-svn: 70902

llvm/lib/Target/X86/X86FastISel.cpp

@@ -30,6 +30,7 @@
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Target/TargetOptions.h"
 using namespace llvm;
 
 namespace {
@@ -1115,6 +1116,11 @@ bool X86FastISel::X86SelectCall(Instruction *I) {
       CC != CallingConv::X86_FastCall)
     return false;
 
+  // On X86, -tailcallopt changes the fastcc ABI. FastISel doesn't
+  // handle this for now.
+  if (CC == CallingConv::Fast && PerformTailCallOpt)
+    return false;
+
   // Let SDISel handle vararg functions.
   const PointerType *PT = cast<PointerType>(CS.getCalledValue()->getType());
   const FunctionType *FTy = cast<FunctionType>(PT->getElementType());

llvm/test/CodeGen/X86/fast-isel-tailcall.ll

@@ -0,0 +1,13 @@
+; RUN: llvm-as < %s | llc -fast-isel -tailcallopt -march=x86 | not grep add
+; PR4154
+
+; On x86, -tailcallopt changes the ABI so the caller shouldn't readjust
+; the stack pointer after the call in this code.
+
+define i32 @stub(i8* %t0) nounwind {
+entry:
+        %t1 = load i32* inttoptr (i32 139708680 to i32*)         ; <i32> [#uses=1]
+        %t2 = bitcast i8* %t0 to i32 (i32)*               ; <i32 (i32)*> [#uses=1]
+        %t3 = call fastcc i32 %t2(i32 %t1)         ; <i32> [#uses=1]
+        ret i32 %t3
+}