[PATCH] D64713: [InstCombine] X *fast (C ? 1.0 : 0.0) -> C ? X : 0.0

[Jay Foad via Phabricator via llvm-commits]

foad marked an inline comment as done.
foad added inline comments.


================
Comment at: llvm/test/Transforms/InstCombine/mul.ll:522-530
+define i32 @mul_div_select(i32 %x, i32 %y, i1 %c) {
+; CHECK-LABEL: @mul_div_select(
+; CHECK-NEXT:    [[MUL:%.*]] = select i1 [[C:%.*]], i32 [[X:%.*]], i32 [[Y:%.*]]
+; CHECK-NEXT:    ret i32 [[MUL]]
+;
+  %div = udiv exact i32 %x, %y
+  %sel = select i1 %c, i32 %div, i32 1
----------------
spatel wrote:
> foad wrote:
> > spatel wrote:
> > > Is this test changed by this patch? If not, it shouldn't be here.
> > Yes. Without this patch, this test does not get simplified at all.
> Ok, then please commit this test with baseline CHECK lines as another preliminary NFC step ahead of this patch.
I don't really understand why you're suggesting to do that with this test case, but not with the other tests I added. There really is not much difference between them.

Perhaps it would be clearer if I split my original patch into two:
1. Pass fast math flags in to the calls to simplifyBinOp.
2. Add the `X op (C ? P : Q) -> C ? (X op P) : (X op Q)` combines that are really the main point of the patch.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D64713/new/

https://reviews.llvm.org/D64713