[llvm] r210789 - Disable the load/store optimization pass for Thumb-1.

Eric Christopher echristo at gmail.com
Sat Jun 14 18:48:10 PDT 2014 

On Jun 14, 2014 6:39 PM, "David Blaikie" <dblaikie at gmail.com> wrote:
>
> I know already, but it might be useful to explain why (especially
> given that there are other examples of similar code there already).
>

Good idea. :)

> My half-baked attempt: James: the subtarget may vary from function to
> function (in Eric's glorious ifunc future) and he'd like to have just
> one pass pipeline that can be used for all functions, even across
> subtarget variations. While the world isn't there yet, it'd be nice to
> avoid making more work.
>
> Eric - are there passes that already do this? Precedent to point to
> for an example of the way you think will work? Or is it all backwards
> for now?

X86, PPC, aarch64, and I thought arm all did it this way. I fixed them a
while back.

-eric

>
> - David
>
> On Sat, Jun 14, 2014 at 6:27 PM, Eric Christopher <echristo at gmail.com>
wrote:
> > Please don't do this in this way, just have the pass return that it did
no
> > work rather than conditionally including it in the pipeline.
> >
> > Thanks. :)
> >
> > -eric
> >
> > On Jun 12, 2014 8:29 AM, "James Molloy" <james.molloy at arm.com> wrote:
> >>
> >> Author: jamesm
> >> Date: Thu Jun 12 10:18:33 2014
> >> New Revision: 210789
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=210789&view=rev
> >> Log:
> >> Disable the load/store optimization pass for Thumb-1.
> >>
> >> Moritz's changes have improved codegen a lot, but further testing
showed
> >> significant correctness problems. Disable by default until these have
been
> >> worked out.
> >>
> >> Patch by Moritz Roth!
> >>
> >> Modified:
> >>     llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp
> >>     llvm/trunk/test/CodeGen/Thumb/2014-06-10-thumb1-ldst-opt-bug.ll
> >>     llvm/trunk/test/CodeGen/Thumb/dyn-stackalloc.ll
> >>     llvm/trunk/test/CodeGen/Thumb/thumb-ldm.ll
> >>     llvm/trunk/test/CodeGen/Thumb/thumb-memcpy-ldm-stm.ll
> >>
> >> Modified: llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp
> >> URL:
> >>
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp?rev=210789&r1=210788&r2=210789&view=diff
> >>
> >>
==============================================================================
> >> --- llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp (original)
> >> +++ llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp Thu Jun 12 10:18:33
> >> 2014
> >> @@ -265,7 +265,8 @@ bool ARMPassConfig::addInstSelector() {
> >>  }
> >>
> >>  bool ARMPassConfig::addPreRegAlloc() {
> >> -  if (getOptLevel() != CodeGenOpt::None)
> >> +  // FIXME: Temporarily disabling Thumb-1 pre-RA Load/Store
optimization
> >> pass
> >> +  if (getOptLevel() != CodeGenOpt::None &&
> >> !getARMSubtarget().isThumb1Only())
> >>      addPass(createARMLoadStoreOptimizationPass(true));
> >>    if (getOptLevel() != CodeGenOpt::None &&
> >> getARMSubtarget().isCortexA9())
> >>      addPass(createMLxExpansionPass());
> >> @@ -280,8 +281,11 @@ bool ARMPassConfig::addPreRegAlloc() {
> >>
> >>  bool ARMPassConfig::addPreSched2() {
> >>    if (getOptLevel() != CodeGenOpt::None) {
> >> -    addPass(createARMLoadStoreOptimizationPass());
> >> -    printAndVerify("After ARM load / store optimizer");
> >> +    // FIXME: Temporarily disabling Thumb-1 post-RA Load/Store
> >> optimization pass
> >> +    if (!getARMSubtarget().isThumb1Only()) {
> >> +      addPass(createARMLoadStoreOptimizationPass());
> >> +      printAndVerify("After ARM load / store optimizer");
> >> +    }
> >>
> >>      if (getARMSubtarget().hasNEON())
> >>        addPass(createExecutionDependencyFixPass(&ARM::DPRRegClass));
> >>
> >> Modified:
llvm/trunk/test/CodeGen/Thumb/2014-06-10-thumb1-ldst-opt-bug.ll
> >> URL:
> >>
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb/2014-06-10-thumb1-ldst-opt-bug.ll?rev=210789&r1=210788&r2=210789&view=diff
> >>
> >>
==============================================================================
> >> --- llvm/trunk/test/CodeGen/Thumb/2014-06-10-thumb1-ldst-opt-bug.ll
> >> (original)
> >> +++ llvm/trunk/test/CodeGen/Thumb/2014-06-10-thumb1-ldst-opt-bug.ll Thu
> >> Jun 12 10:18:33 2014
> >> @@ -1,4 +1,5 @@
> >>  ; RUN: llc < %s -mtriple=thumbv6m-eabi -o - | FileCheck %s
> >> +; XFAIL: *
> >>
> >>  define void @foo(i32* %A) #0 {
> >>  entry:
> >>
> >> Modified: llvm/trunk/test/CodeGen/Thumb/dyn-stackalloc.ll
> >> URL:
> >>
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb/dyn-stackalloc.ll?rev=210789&r1=210788&r2=210789&view=diff
> >>
> >>
==============================================================================
> >> --- llvm/trunk/test/CodeGen/Thumb/dyn-stackalloc.ll (original)
> >> +++ llvm/trunk/test/CodeGen/Thumb/dyn-stackalloc.ll Thu Jun 12 10:18:33
> >> 2014
> >> @@ -1,5 +1,5 @@
> >> -; RUN: llc < %s -mtriple=thumb-apple-darwin -disable-cgp-branch-opts
> >> -disable-post-ra | FileCheck %s -check-prefix=CHECK
-check-prefix=RA_GREEDY
> >> -; RUN: llc < %s -mtriple=thumb-apple-darwin -disable-cgp-branch-opts
> >> -disable-post-ra -regalloc=basic | FileCheck %s -check-prefix=CHECK
> >> -check-prefix=RA_BASIC
> >> +; RUN: llc < %s -mtriple=thumb-apple-darwin -disable-cgp-branch-opts
> >> -disable-post-ra | FileCheck %s
> >> +; RUN: llc < %s -mtriple=thumb-apple-darwin -disable-cgp-branch-opts
> >> -disable-post-ra -regalloc=basic | FileCheck %s
> >>
> >>         %struct.state = type { i32, %struct.info*, float**, i32, i32,
i32,
> >> i32, i32, i32, i32, i32, i32, i64, i64, i64, i64, i64, i64, i8* }
> >>         %struct.info = type { i32, i32, i32, i32, i32, i32, i32, i8* }
> >> @@ -45,8 +45,7 @@ define void @t2(%struct.comment* %vc, i8
> >>  ; CHECK: sub sp, #
> >>  ; CHECK: mov r[[R0:[0-9]+]], sp
> >>  ; CHECK: str r{{[0-9+]}}, [r[[R0]]
> >> -; RA_GREEDY: str r{{[0-9+]}}, [r[[R0]]
> >> -; RA_BASIC: stm r[[R0]]!
> >> +; CHECK: str r{{[0-9+]}}, [r[[R0]]
> >>  ; CHECK-NOT: ldr r0, [sp
> >>  ; CHECK: mov r[[R1:[0-9]+]], sp
> >>  ; CHECK: subs r[[R2:[0-9]+]], r[[R1]], r{{[0-9]+}}
> >>
> >> Modified: llvm/trunk/test/CodeGen/Thumb/thumb-ldm.ll
> >> URL:
> >>
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb/thumb-ldm.ll?rev=210789&r1=210788&r2=210789&view=diff
> >>
> >>
==============================================================================
> >> --- llvm/trunk/test/CodeGen/Thumb/thumb-ldm.ll (original)
> >> +++ llvm/trunk/test/CodeGen/Thumb/thumb-ldm.ll Thu Jun 12 10:18:33 2014
> >> @@ -1,4 +1,5 @@
> >>  ; RUN: llc < %s -mtriple=thumbv6m-eabi -o - | FileCheck %s
> >> +; XFAIL: *
> >>
> >>  @X = external global [0 x i32]          ; <[0 x i32]*> [#uses=5]
> >>
> >>
> >> Modified: llvm/trunk/test/CodeGen/Thumb/thumb-memcpy-ldm-stm.ll
> >> URL:
> >>
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb/thumb-memcpy-ldm-stm.ll?rev=210789&r1=210788&r2=210789&view=diff
> >>
> >>
==============================================================================
> >> --- llvm/trunk/test/CodeGen/Thumb/thumb-memcpy-ldm-stm.ll (original)
> >> +++ llvm/trunk/test/CodeGen/Thumb/thumb-memcpy-ldm-stm.ll Thu Jun 12
> >> 10:18:33 2014
> >> @@ -1,4 +1,5 @@
> >>  ; RUN: llc -mtriple=thumbv6m-eabi %s -o - | FileCheck %s
> >> +; XFAIL: *
> >>
> >>  @d = external global [64 x i32]
> >>  @s = external global [64 x i32]
> >>
> >>
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> >
> >
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