http://llvm.org/bugs/show_bug.cgi?id=19446
Bug ID: 19446
Summary: Loop vectorizer cannot generate runtime checks for
uniform loads
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Loop Optimizer
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 12382
--> http://llvm.org/bugs/attachment.cgi?id=12382&action=edit
test case showing uniform load
Currently, AccessAnalysis::canCheckPtrAtRT calls hasComputableBounds, and
hasComputableBounds has:
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PtrScev);
if (!AR)
return false;
return AR->isAffine();
so we don't generate runtime checks for uniform loads. For example, if the loop
has:
%12 = load double* %ref3, align 8, !tbaa !4
%arrayidx = getelementptr inbounds [10000000 x double]* @c, i64 0, i64
%.idx..015
%13 = load double* %arrayidx, align 8, !tbaa !4
%mul5 = fmul double %12, %13
where %ref3 is loop invariant, this loop will not vectorize because we won't
generate the necessary runtime check. I've attached a (simple) test case.
--
You are receiving this mail because:
You are on the CC list for the bug.
_______________________________________________
LLVMbugs mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/llvmbugs
