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

[Xinliang David Li via llvm-commits]

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.

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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