Fix for PR7193 was overly conservative. The only case where sibcall callee
address cannot be allocated a register is in 32-bit mode where the first
three arguments are marked inreg. In that case EAX, EDX, and ECX will be
used for argument passing.
This fixes PR7610.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108327 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 1a63474..937d510 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2458,17 +2458,23 @@
// 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;
}
}
}