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[PowerPC] Don't generate ST_VSR_SCAL_INT if power8-vector is disabled, fix PR45297

Authored by lkail on Mar 25 2020, 7:00 AM.



In, it fails selecting instructions for PPCISD::ST_VSR_SCAL_INT. The reason it generate the PPCISD::ST_VSR_SCAL_INT with -power8-vector in IR is PPC's combiner checks hasP8Altivec rather than hasP8Vector. This patch should resolve PR45297.

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lkail created this revision.Mar 25 2020, 7:00 AM
lkail edited the summary of this revision. (Show Details)Mar 25 2020, 7:08 AM

Can you fix the title of this? "Fix PR45297" is not very descriptive unless someone also reviews the PR.

lkail retitled this revision from [PowerPC] Fix PR45297 to [PowerPC] Don't generate ST_VSR_SCAL_INT if power8-vector is disabled, fix PR45297.Mar 25 2020, 6:52 PM
lkail added a reviewer: jhibbits.
steven.zhang accepted this revision.Mar 25 2020, 9:30 PM

LGTM. Please hold on for some days in case someone else has concern.

This revision is now accepted and ready to land.Mar 25 2020, 9:30 PM

A couple minor suggestions. If you agree with them, feel free to land them as an NFC update to the test before commiting this patch.


Pre-commiting the test to show the intended change in behaviour is a really good idea. I think it would be more effective if we check for the error we are tying to fix though:

; RUN: not --crash llc -verify-machineinstrs \
; RUN:   -mtriple=powerpc64le-unknown-linux-gnu -mattr=+altivec \
; RUN:   -mattr=-power8-vector -mattr=-vsx < %s 2>&1 | FileCheck %s

; CHECK: LLVM ERROR: Cannot select: t{{[0-9]+}}: ch = PPCISD::ST_VSR_SCAL_INT<(store 4 into @Global)>

Nit: can we store to something other then undef? Maybe changing the IR to:

@Global = dso_local global i32 55, align 4

define dso_local void @test(float %0) local_unnamed_addr {
  %1 = fptosi float %0 to i32
  store i32 %1, i32* @Global, align 4
  ret void
lkail updated this revision to Diff 253043.Mar 26 2020, 10:00 PM

Address @sfertile 's comment.

lkail marked 2 inline comments as done.Mar 26 2020, 10:01 PM
lkail updated this revision to Diff 253044.Mar 26 2020, 10:41 PM
sfertile accepted this revision.Mar 27 2020, 8:16 AM

Thank you for the updates. One minor comment, but patch LGTM.


Do we want to use -ppc-asm-full-reg-names to make the assembly easier to read?

This revision was automatically updated to reflect the committed changes.