[llvm-commits] CVS: llvm/lib/Target/X86/InstSelectSimple.cpp

[Chris Lattner]

Changes in directory llvm/lib/Target/X86:

InstSelectSimple.cpp updated: 1.245 -> 1.246

---
Log message:

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



---
Diffs of the changes:  (+8 -1)

Index: llvm/lib/Target/X86/InstSelectSimple.cpp
diff -u llvm/lib/Target/X86/InstSelectSimple.cpp:1.245 llvm/lib/Target/X86/InstSelectSimple.cpp:1.246
--- llvm/lib/Target/X86/InstSelectSimple.cpp:1.245	Tue May  4 14:35:11 2004
+++ llvm/lib/Target/X86/InstSelectSimple.cpp	Fri May  7 14:55:55 2004
@@ -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();