[PATCH] D21405: [PGO] IRPGO pre-cleanup pass changes

[Rong Xu via llvm-commits]

On Wed, Jun 29, 2016 at 2:56 PM, Xinliang David Li <davidxl at google.com>
wrote:

>
>
> On Wed, Jun 29, 2016 at 2:51 PM, Rong Xu <xur at google.com> wrote:
>
>> xur updated this revision to Diff 62287.
>> xur added a comment.
>>
>> ere is the updated patch. Changes are:
>> (1) Removed options preinline as suggested by mehdi.
>> (2) Updated the cleanup passes list.
>>
>> I used google internal benchmarks to measure the performance. The cleanup
>> pass have ~2% geo-mean on the profile-generate performance. The largest
>> saving is 17%.
>>
>
>
> You may want to clarify it is the effect of those passes other than
> pre-inline.
>

Yes. Thanks for pointing this out: This numbers are measured with
pre-intrumentation inline always on, just on/off these cleanup passes.


>
> David
>
>>
>> David's suggestion on using SROA and EarlyCSE is good. It has positive
>> impacts on a number of programs (largest ~10%)
>>
>> Jumpthreading actually helps a few programs also (~3%).
>>
>> In this patch, I propose to use
>> SROA  + EArlyCSE + CFGSimplification + InstructionCombining
>> and remove the rest.
>>
>>
>> http://reviews.llvm.org/D21405
>>
>> Files:
>>   lib/Transforms/IPO/PassManagerBuilder.cpp
>>   test/Transforms/PGOProfile/preinline.ll
>>
>> Index: test/Transforms/PGOProfile/preinline.ll
>> ===================================================================
>> --- /dev/null
>> +++ test/Transforms/PGOProfile/preinline.ll
>> @@ -0,0 +1,20 @@
>> +; RUN: opt < %s -O2 -profile-generate=default.profraw -S | FileCheck %s
>> --check-prefix=GEN
>> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>> +target triple = "x86_64-unknown-linux-gnu"
>> +
>> +define i32 @foo(i32 %i) {
>> +entry:
>> +; GEN: %pgocount = load i64, i64* getelementptr inbounds ([1 x i64], [1
>> x i64]* @__profc_foo
>> +; GEN-NOT: %pgocount.i = load i64, i64* getelementptr inbounds ([1 x
>> i64], [1 x i64]* @__profc__stdin__bar
>> +  %call = call i32 @bar()
>> +  %add = add nsw i32 %i, %call
>> +  ret i32 %add
>> +}
>> +
>> +define internal i32 @bar() {
>> +entry:
>> +  %call = call i32 (...) @bar1()
>> +  ret i32 %call
>> +}
>> +
>> +declare i32 @bar1(...)
>> Index: lib/Transforms/IPO/PassManagerBuilder.cpp
>> ===================================================================
>> --- lib/Transforms/IPO/PassManagerBuilder.cpp
>> +++ lib/Transforms/IPO/PassManagerBuilder.cpp
>> @@ -114,6 +114,10 @@
>>      "enable-loop-versioning-licm", cl::init(false), cl::Hidden,
>>      cl::desc("Enable the experimental Loop Versioning LICM pass"));
>>
>> +static cl::opt<bool>
>> +    DisablePreInliner("disable-preinline", cl::init(false), cl::Hidden,
>> +                      cl::desc("Disable pre-instrumentation inliner"));
>> +
>>  PassManagerBuilder::PassManagerBuilder() {
>>      OptLevel = 2;
>>      SizeLevel = 0;
>> @@ -202,8 +206,30 @@
>>    FPM.add(createLowerExpectIntrinsicPass());
>>  }
>>
>> +// Get the inline threshold for pre-instrumentation inline.
>> +static int computePreInlineThresholdFromOptLevels(unsigned OptLevel,
>> +                                                  unsigned SizeOptLevel)
>> {
>> +  if (SizeOptLevel == 1) // -Os
>> +    return 75;
>> +  if (SizeOptLevel == 2) // -Oz
>> +    return 25;
>> +  return 75;
>> +}
>> +
>>  // Do PGO instrumentation generation or use pass as the option specified.
>>  void PassManagerBuilder::addPGOInstrPasses(legacy::PassManagerBase &MPM)
>> {
>> +  if (PGOInstrGen.empty() && PGOInstrUse.empty())
>> +    return;
>> +  if (OptLevel > 0 && !DisablePreInliner) {
>> +    // Create preinline pass.
>> +    MPM.add(createFunctionInliningPass(
>> +        computePreInlineThresholdFromOptLevels(OptLevel, SizeLevel)));
>> +    MPM.add(createSROAPass());
>> +    MPM.add(createEarlyCSEPass());             // Catch trivial
>> redundancies
>> +    MPM.add(createCFGSimplificationPass());    // Merge & remove BBs
>> +    MPM.add(createInstructionCombiningPass()); // Combine silly seq's
>> +    addExtensionsToPM(EP_Peephole, MPM);
>> +  }
>>    if (!PGOInstrGen.empty()) {
>>      MPM.add(createPGOInstrumentationGenLegacyPass());
>>      // Add the profile lowering pass.
>>
>>
>>
>
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