[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

[Chris Lattner]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

SelectionDAG.cpp updated: 1.72 -> 1.73
---
Log message:

Remove some redundant checks, add a couple of new ones.  This allows us to
compile this:

int foo (unsigned long a, unsigned long long g) {
  return a >= g;
}

To:

foo:
        movl 8(%esp), %eax
        cmpl %eax, 4(%esp)
        setae %al
        cmpl $0, 12(%esp)
        sete %cl
        andb %al, %cl
        movzbl %cl, %eax
        ret

instead of:

foo:
        movl 8(%esp), %eax
        cmpl %eax, 4(%esp)
        setae %al
        movzbw %al, %cx
        movl 12(%esp), %edx
        cmpl $0, %edx
        sete %al
        movzbw %al, %ax
        cmpl $0, %edx
        cmove %cx, %ax
        movzbl %al, %eax
        ret




---
Diffs of the changes:  (+5 -7)

 SelectionDAG.cpp |   12 +++++-------
 1 files changed, 5 insertions(+), 7 deletions(-)


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.72 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.73
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.72	Mon Apr 11 19:28:49 2005
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp	Mon Apr 11 21:54:39 2005
@@ -960,12 +960,6 @@
 
     if (VT == MVT::i1) {  // Boolean SELECT
       if (N2C) {
-        if (N3C) {
-          if (N2C->getValue()) // select C, 1, 0 -> C
-            return N1;
-          return getNode(ISD::XOR, VT, N1, N3); // select C, 0, 1 -> ~C
-        }
-
         if (N2C->getValue())   // select C, 1, X -> C | X
           return getNode(ISD::OR, VT, N1, N3);
         else                   // select C, 0, X -> ~C & X
@@ -980,6 +974,11 @@
         else                   // select C, X, 0 -> C & X
           return getNode(ISD::AND, VT, N1, N2);
       }
+
+      if (N1 == N2)   // X ? X : Y --> X ? 1 : Y --> X | Y
+        return getNode(ISD::OR, VT, N1, N3);
+      if (N1 == N3)   // X ? Y : X --> X ? Y : 0 --> X & Y
+        return getNode(ISD::AND, VT, N1, N2);
     }
 
     // If this is a selectcc, check to see if we can simplify the result.
@@ -1001,7 +1000,6 @@
               N2.getOperand(0) == N3)
             return getNode(ISD::FABS, VT, N3);
         }
-
     }
     break;
   case ISD::BRCOND: