When emitting code for an add, don't force a SCEVUnknown wrapper around

a hoisted intermediate result if the intermediate result isn't an
Instruction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100884 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-04-09 19:14:31 +00:00
parent 4a2a683366
commit f8d0578e4c
2 changed files with 41 additions and 3 deletions

View File

@ -705,10 +705,11 @@ Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, Sum);
} else if (const PointerType *PTy = dyn_cast<PointerType>(Op->getType())) {
// The running sum is an integer, and there's a pointer at this level.
// Try to form a getelementptr. Use a SCEVUnknown so that we don't
// re-analyze the instructions that we just emitted.
// Try to form a getelementptr. If the running sum is instructions,
// use a SCEVUnknown to avoid re-analyzing them.
SmallVector<const SCEV *, 4> NewOps;
NewOps.push_back(SE.getUnknown(Sum));
NewOps.push_back(isa<Instruction>(Sum) ? SE.getUnknown(Sum) :
SE.getSCEV(Sum));
for (++I; I != E && I->first == CurLoop; ++I)
NewOps.push_back(I->second);
Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op));

View File

@ -0,0 +1,37 @@
; RUN: opt < %s -loop-reduce -S | not grep uglygep
; LSR shouldn't consider %t8 to be an interesting user of %t6, and it
; should be able to form pretty GEPs.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-unknown-linux-gnu"
define void @Z4() nounwind {
bb:
br label %bb3
bb1: ; preds = %bb3
br i1 undef, label %bb10, label %bb2
bb2: ; preds = %bb1
%t = add i64 %t4, 1 ; <i64> [#uses=1]
br label %bb3
bb3: ; preds = %bb2, %bb
%t4 = phi i64 [ %t, %bb2 ], [ 0, %bb ] ; <i64> [#uses=3]
br label %bb1
bb10: ; preds = %bb9
%t7 = icmp eq i64 %t4, 0 ; <i1> [#uses=1]
%t3 = add i64 %t4, 16 ; <i64> [#uses=1]
br label %bb14
bb14: ; preds = %bb14, %bb10
%t2 = getelementptr inbounds i8* undef, i64 %t4 ; <i8*> [#uses=1]
store i8 undef, i8* %t2
%t6 = load float** undef
%t8 = bitcast float* %t6 to i8* ; <i8*> [#uses=1]
%t9 = getelementptr inbounds i8* %t8, i64 %t3 ; <i8*> [#uses=1]
store i8 undef, i8* %t9
br label %bb14
}