Changes in directory llvm/lib/CodeGen/SelectionDAG:
DAGCombiner.cpp updated: 1.285 -> 1.286
---
Log message:
Codegen integer abs more efficiently using the trick from the PPC CWG. This
improves codegen on many architectures. Tests committed as CodeGen/*/iabs.ll
X86 Old: X86 New:
_test: _test:
movl 4(%esp), %ecx movl 4(%esp), %eax
movl %ecx, %eax movl %eax, %ecx
negl %eax sarl $31, %ecx
testl %ecx, %ecx addl %ecx, %eax
cmovns %ecx, %eax xorl %ecx, %eax
ret ret
PPC Old: PPC New:
_test: _test:
cmpwi cr0, r3, -1 srawi r2, r3, 31
neg r2, r3 add r3, r3, r2
bgt cr0, LBB1_2 ; xor r3, r3, r2
LBB1_1: ; blr
mr r3, r2
LBB1_2: ;
blr
ARM Old: ARM New:
_test: _test:
rsb r3, r0, #0 add r3, r0, r0, asr #31
cmp r0, #0 eor r0, r3, r0, asr #31
movge r3, r0 bx lr
mov r0, r3
bx lr
Thumb Old: Thumb New:
_test: _test:
neg r2, r0 asr r2, r0, #31
cmp r0, #0 add r0, r0, r2
bge LBB1_2 eor r0, r2
LBB1_1: @ bx lr
cpy r0, r2
LBB1_2: @
bx lr
Sparc Old: Sparc New:
test: test:
save -96, %o6, %o6 save -96, %o6, %o6
sethi 0, %l0 sra %i0, 31, %l0
sub %l0, %i0, %l0 add %i0, %l0, %l1
subcc %i0, -1, %l1 xor %l1, %l0, %i0
bg .BB1_2 restore %g0, %g0, %g0
nop retl
.BB1_1: nop
or %g0, %l0, %i0
.BB1_2:
restore %g0, %g0, %g0
retl
nop
It also helps alpha/ia64 :)
---
Diffs of the changes: (+18 -4)
DAGCombiner.cpp | 22 ++++++++++++++++++----
1 files changed, 18 insertions(+), 4 deletions(-)
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.285
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.286
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.285 Mon Apr 2 16:36:32 2007
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Apr 11 00:11:38 2007
@@ -4159,13 +4159,27 @@
// Check to see if this is an integer abs. select_cc setl[te] X, 0, -X, X ->
// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N1C && N1C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE) &&
- N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1)) {
- if (ConstantSDNode *SubC = dyn_cast<ConstantSDNode>(N2.getOperand(0))) {
+ N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1) &&
+ N2.getOperand(0) == N1 && MVT::isInteger(N0.getValueType())) {
+ MVT::ValueType XType = N0.getValueType();
+ SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0,
+ DAG.getConstant(MVT::getSizeInBits(XType)-1,
+ TLI.getShiftAmountTy()));
+ SDOperand Add = DAG.getNode(ISD::ADD, XType, N0, Shift);
+ AddToWorkList(Shift.Val);
+ AddToWorkList(Add.Val);
+ return DAG.getNode(ISD::XOR, XType, Add, Shift);
+ }
+ // Check to see if this is an integer abs. select_cc setgt X, -1, X, -X ->
+ // Y = sra (X, size(X)-1); xor (add (X, Y), Y)
+ if (N1C && N1C->isAllOnesValue() && CC == ISD::SETGT &&
+ N0 == N2 && N3.getOpcode() == ISD::SUB && N0 == N3.getOperand(1)) {
+ if (ConstantSDNode *SubC = dyn_cast<ConstantSDNode>(N3.getOperand(0))) {
MVT::ValueType XType = N0.getValueType();
if (SubC->isNullValue() && MVT::isInteger(XType)) {
SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0,
DAG.getConstant(MVT::getSizeInBits(XType)-1,
- TLI.getShiftAmountTy()));
+ TLI.getShiftAmountTy()));
SDOperand Add = DAG.getNode(ISD::ADD, XType, N0, Shift);
AddToWorkList(Shift.Val);
AddToWorkList(Add.Val);
@@ -4173,7 +4187,7 @@
}
}
}
-
+
return SDOperand();
}
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
