[llvm-commits] CVS: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

LoopStrengthReduce.cpp updated: 1.54 -> 1.55
---
Log message:

implement Transforms/LoopStrengthReduce/dont-hoist-simple-loop-constants.ll.

We used to emit this code for it:

_test:
        li r2, 1     ;; Value tying up a register for the whole loop
        li r5, 0
LBB_test_1:     ; no_exit.2
        or r6, r5, r5
        li r5, 0
        stw r5, 0(r3)
        addi r5, r6, 1
        addi r3, r3, 4
        add r7, r2, r5  ;; should be addi r7, r5, 1
        cmpwi cr0, r7, 701
        blt cr0, LBB_test_1     ; no_exit.2
LBB_test_2:     ; loopexit.2.loopexit
        addi r2, r6, 2
        stw r2, 0(r4)
        blr

now we emit this:

_test:
        li r2, 0
LBB_test_1:     ; no_exit.2
        or r5, r2, r2
        li r2, 0
        stw r2, 0(r3)
        addi r3, r3, 4
        addi r2, r5, 1
        addi r6, r5, 2   ;; whoa, fold those adds!
        cmpwi cr0, r6, 701
        blt cr0, LBB_test_1     ; no_exit.2
LBB_test_2:     ; loopexit.2.loopexit
        addi r2, r5, 2
        stw r2, 0(r4)
        blr

more improvement coming.



---
Diffs of the changes:  (+1 -1)

 LoopStrengthReduce.cpp |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)


Index: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
diff -u llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.54 llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.55
--- llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:1.54	Wed Aug 17 16:22:41 2005
+++ llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp	Fri Sep  9 20:18:45 2005
@@ -826,7 +826,7 @@
     // this by forcing a noop cast to be inserted into the preheader in this
     // case.
     if (Constant *C = dyn_cast<Constant>(BaseV))
-      if (!C->isNullValue()) {
+      if (!C->isNullValue() && !isTargetConstant(Base)) {
         // We want this constant emitted into the preheader!
         BaseV = new CastInst(BaseV, BaseV->getType(), "preheaderinsert",
                              PreInsertPt);