From b18004c13c0c494305b0ce1d748049f8c580bd99 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 26 Nov 2009 18:35:46 +0000 Subject: fix two transposed lines duncan caught and add an explanatory comment. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89958 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/ValueTracking.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index 37d5ad3..5439bbf 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -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(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 -- cgit v1.1