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

James Molloy james at jamesmolloy.co.uk
Sun Jun 15 11:41:02 PDT 2014 

Hi Eric,

Sure. Sorry, I didn't know there was a preferred way of doing this. The
reason I did it like I did was simply that was how it was disabled before
Moritz reenabled it!

I'll bear in mind for the future.
Cheers,

James


On 15 June 2014 02:48, Eric Christopher <echristo at gmail.com> wrote:

>
> 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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