X86: More efficient legalization of wide integer compares
In particular, this makes the code for 64-bit compares on 32-bit targets
much more efficient.
Example:
define i32 @test_slt(i64 %a, i64 %b) {
entry:
%cmp = icmp slt i64 %a, %b
br i1 %cmp, label %bb1, label %bb2
bb1:
ret i32 1
bb2:
ret i32 2
}
Before this patch:
test_slt:
movl 4(%esp), %eax
movl 8(%esp), %ecx
cmpl 12(%esp), %eax
setae %al
cmpl 16(%esp), %ecx
setge %cl
je .LBB2_2
movb %cl, %al
.LBB2_2:
testb %al, %al
jne .LBB2_4
movl $1, %eax
retl
.LBB2_4:
movl $2, %eax
retl
After this patch:
test_slt:
movl 4(%esp), %eax
movl 8(%esp), %ecx
cmpl 12(%esp), %eax
sbbl 16(%esp), %ecx
jge .LBB1_2
movl $1, %eax
retl
.LBB1_2:
movl $2, %eax
retl
Differential Revision: http://reviews.llvm.org/D14496
llvm-svn: 253572
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index e3a11cd..b465ffb 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1242,7 +1242,8 @@
case ISD::SETCC:
case ISD::BR_CC: {
unsigned CCOperand = Node->getOpcode() == ISD::SELECT_CC ? 4 :
- Node->getOpcode() == ISD::SETCC ? 2 : 1;
+ Node->getOpcode() == ISD::SETCC ? 2 :
+ Node->getOpcode() == ISD::SETCCE ? 3 : 1;
unsigned CompareOperand = Node->getOpcode() == ISD::BR_CC ? 2 : 0;
MVT OpVT = Node->getOperand(CompareOperand).getSimpleValueType();
ISD::CondCode CCCode =