Make comparisons against the null pointer as efficient as integer comparisons
against zero. In particular, don't emit:
mov %ESI, 0
cmp %ECX, %ESI
instead, emit:
test %ECX, %ECX
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13407 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/InstSelectSimple.cpp b/lib/Target/X86/InstSelectSimple.cpp
index da2175b..4597a82 100644
--- a/lib/Target/X86/InstSelectSimple.cpp
+++ b/lib/Target/X86/InstSelectSimple.cpp
@@ -829,7 +829,14 @@
unsigned Op0r = getReg(Op0, MBB, IP);
// Special case handling of: cmp R, i
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ if (isa<ConstantPointerNull>(Op1)) {
+ if (OpNum < 2) // seteq/setne -> test
+ BuildMI(*MBB, IP, X86::TEST32rr, 2).addReg(Op0r).addReg(Op0r);
+ else
+ BuildMI(*MBB, IP, X86::CMP32ri, 2).addReg(Op0r).addImm(0);
+ return OpNum;
+
+ } else if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
if (Class == cByte || Class == cShort || Class == cInt) {
unsigned Op1v = CI->getRawValue();