fix two transposed lines duncan caught and add an explanatory comment.

llvm-svn: 89958
This commit is contained in:
Chris Lattner 2009-11-26 18:35:46 +00:00
parent 9aa846956e
commit d7cabea8ca
1 changed files with 4 additions and 1 deletions

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@ -1064,12 +1064,15 @@ const Value *llvm::DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
uint64_t Scale = TD->getTypeAllocSize(*GTI);
// Use GetLinearExpression to decompose the index into a C1*V+C2 form.
unsigned Width = cast<IntegerType>(Index->getType())->getBitWidth();
APInt IndexScale(Width, 0), IndexOffset(Width, 0);
Index = GetLinearExpression(Index, IndexScale, IndexOffset, TD);
Scale *= IndexScale.getZExtValue();
// The GEP index scale ("Scale") scales C1*V+C2, yielding (C1*V+C2)*Scale.
// This gives us an aggregate computation of (C1*Scale)*V + C2*Scale.
BaseOffs += IndexOffset.getZExtValue()*Scale;
Scale *= IndexScale.getZExtValue();
// If we already had an occurrance of this index variable, merge this