Changes in directory llvm/lib/Target/PowerPC:
PPCISelLowering.cpp updated: 1.120 -> 1.121
README_ALTIVEC.txt updated: 1.7 -> 1.8
---
Log message:
Implement an item from the readme, folding vcmp/vcmp. instructions with
identical instructions into a single instruction. For example, for:
void test(vector float *x, vector float *y, int *P) {
int v = vec_any_out(*x, *y);
*x = (vector float)vec_cmpb(*x, *y);
*P = v;
}
we now generate:
_test:
mfspr r2, 256
oris r6, r2, 49152
mtspr 256: http://llvm.cs.uiuc.edu/PR256 , r6
lvx v0, 0, r4
lvx v1, 0, r3
vcmpbfp. v0, v1, v0
mfcr r4, 2
stvx v0, 0, r3
rlwinm r3, r4, 27, 31, 31
xori r3, r3, 1
stw r3, 0(r5)
mtspr 256: http://llvm.cs.uiuc.edu/PR256 , r2
blr
instead of:
_test:
mfspr r2, 256
oris r6, r2, 57344
mtspr 256: http://llvm.cs.uiuc.edu/PR256 , r6
lvx v0, 0, r4
lvx v1, 0, r3
vcmpbfp. v2, v1, v0
mfcr r4, 2
*** vcmpbfp v0, v1, v0
rlwinm r4, r4, 27, 31, 31
stvx v0, 0, r3
xori r3, r4, 1
stw r3, 0(r5)
mtspr 256: http://llvm.cs.uiuc.edu/PR256 , r2
blr
Testcase here: CodeGen/PowerPC/vcmp-fold.ll
---
Diffs of the changes: (+29 -9)
PPCISelLowering.cpp | 29 +++++++++++++++++++++++++++++
README_ALTIVEC.txt | 9 ---------
2 files changed, 29 insertions(+), 9 deletions(-)
Index: llvm/lib/Target/PowerPC/PPCISelLowering.cpp
diff -u llvm/lib/Target/PowerPC/PPCISelLowering.cpp:1.120
llvm/lib/Target/PowerPC/PPCISelLowering.cpp:1.121
--- llvm/lib/Target/PowerPC/PPCISelLowering.cpp:1.120 Thu Mar 30 23:13:27 2006
+++ llvm/lib/Target/PowerPC/PPCISelLowering.cpp Fri Mar 31 00:02:07 2006
@@ -1368,6 +1368,35 @@
return Val;
}
break;
+ case PPCISD::VCMP: {
+ // If a VCMPo node already exists with exactly the same operands as this
+ // node, use its result instead of this node (VCMPo computes both a CR6 and
+ // a normal output).
+ //
+ if (!N->getOperand(0).hasOneUse() &&
+ !N->getOperand(1).hasOneUse() &&
+ !N->getOperand(2).hasOneUse()) {
+
+ // Scan all of the users of the LHS, looking for VCMPo's that match.
+ SDNode *VCMPoNode = 0;
+
+ SDNode *LHSN = N->getOperand(0).Val;
+ for (SDNode::use_iterator UI = LHSN->use_begin(), E = LHSN->use_end();
+ UI != E; ++UI)
+ if ((*UI)->getOpcode() == PPCISD::VCMPo &&
+ (*UI)->getOperand(1) == N->getOperand(1) &&
+ (*UI)->getOperand(2) == N->getOperand(2) &&
+ (*UI)->getOperand(0) == N->getOperand(0)) {
+ VCMPoNode = *UI;
+ break;
+ }
+
+ // If there are non-zero uses of the flag value, use the VCMPo node!
+ if (!VCMPoNode->hasNUsesOfValue(0, 1))
+ return SDOperand(VCMPoNode, 0);
+ }
+ break;
+ }
}
return SDOperand();
Index: llvm/lib/Target/PowerPC/README_ALTIVEC.txt
diff -u llvm/lib/Target/PowerPC/README_ALTIVEC.txt:1.7
llvm/lib/Target/PowerPC/README_ALTIVEC.txt:1.8
--- llvm/lib/Target/PowerPC/README_ALTIVEC.txt:1.7 Thu Mar 30 22:53:21 2006
+++ llvm/lib/Target/PowerPC/README_ALTIVEC.txt Fri Mar 31 00:02:07 2006
@@ -131,15 +131,6 @@
//===----------------------------------------------------------------------===//
-Two identical comparisons in predicate and nonpredicate form like this:
-
-a = vec_cmpb(x, y);
-b = vec_any_out(x, y);
-
-Should turn into one "." compare instruction, not a dot and "nondot" form.
-
-//===----------------------------------------------------------------------===//
-
Instcombine llvm.ppc.altivec.vperm with an immediate into a shuffle operation.
//===----------------------------------------------------------------------===//
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