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
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21244 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 0243ebf..634197c 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -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: