[PATCH] D23854: [LoopAccessAnalysis] Recognize geps that include s/zexts as consecutive memory accesses.

Balaram Makam via llvm-commits llvm-commits at lists.llvm.org
Tue Aug 30 11:23:33 PDT 2016

bmakam added inline comments.

Comment at: lib/Analysis/LoopAccessAnalysis.cpp:1112
@@ +1111,3 @@
+    APInt KnownOne(BitWidth, 0);
+    computeKnownBits(OpA, KnownZero, KnownOne, DL, 0, nullptr, OpA, DT);
+    KnownZero &= ~APInt::getHighBitsSet(BitWidth, 1);
mcrosier wrote:
> bmakam wrote:
> > mcrosier wrote:
> > > bmakam wrote:
> > > > I think it is very rare we ever reach this code. In my testing on spec2k* I did not find any instance.
> > > Balaram,
> > > Do you mean you added an assertion to make sure we never hit this code or that you didn't see any codegen changes for SPEC200X?
> > > 
> > What I meant was I did not see any codegen changes but in retrospect I added assertion and it hits almost all of SPEC200x, so this might impact compile time.
> Alternatively, you might be able to add a statistic (or two) to determine how often we actually hit this code.
6417 accesses were analyzed using computeKnownBits in Spec2kX with several benchmarks hitting between 500-1000 times.


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