Fix for PR7193 was overly conservative. The only case where sibcall callee

[oota-llvm.git] / lib / Target / X86 / X86ISelLowering.cpp

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 1a634744806e53f673dfe4eaadaefe8e5fe7986e..937d51023bdf7fa1711caa0b62ec00bfaf478e68 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2458,17 +2458,23 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
     // If the tailcall address may be in a register, then make sure it's
     // possible to register allocate for it. In 32-bit, the call address can
     // only target EAX, EDX, or ECX since the tail call must be scheduled after
-    // callee-saved registers are restored. In 64-bit, it's RAX, RCX, RDX, RSI,
-    // RDI, R8, R9, R11.
-    if (!isa<GlobalAddressSDNode>(Callee) &&
+    // callee-saved registers are restored. These happen to be the same
+    // registers used to pass 'inreg' arguments so watch out for those.
+    if (!Subtarget->is64Bit() &&
+        !isa<GlobalAddressSDNode>(Callee) &&
         !isa<ExternalSymbolSDNode>(Callee)) {
-      unsigned Limit = Subtarget->is64Bit() ? 8 : 3;
       unsigned NumInRegs = 0;
       for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
         CCValAssign &VA = ArgLocs[i];
-        if (VA.isRegLoc()) {
-          if (++NumInRegs == Limit)
+        if (!VA.isRegLoc())
+          continue;
+        unsigned Reg = VA.getLocReg();
+        switch (Reg) {
+        default: break;
+        case X86::EAX: case X86::EDX: case X86::ECX:
+          if (++NumInRegs == 3)
             return false;
+          break;
         }
       }
     }