[PATCH] D142420: [Flang] Add support to use LTO specific pipelines

[Usman Nadeem via Phabricator via cfe-commits]

mnadeem added a comment.

In D142420#4184825 , @tblah wrote:

> In D142420#4080619 , @mnadeem wrote:
>
>> We have tried full LTO on Aarch64 (without this patch) and have seen a few 
>> 3-8% improvements in SPEC and a 100+% improvement in leslie3d.
>> There were a couple of additional failures in SPEC that we have yet to 
>> inspect but AFAICT no issue with respect to bitcode/assembly changes.
>
> Hi @mnadeem, thanks for this patch. I'm having some trouble reproducing the 
> improvement on leslie3d. Can you share more information about your 
> configuration? Which flags did you use?

`-O3 -flto -mllvm -fdynamic-heap-array` on an Aarch64 device.
It was tested back in January, so if the improvement is not showing up right 
now then it may be possible that some other patch/optimization enabled better 
codegen in non-lto too.


Repository:
  rG LLVM Github Monorepo

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[PATCH] D142420: [Flang] Add support to use LTO specific pipelines

[Tom Eccles via Phabricator via cfe-commits]

tblah added a comment.

In D142420#4080619 , @mnadeem wrote:

> We have tried full LTO on Aarch64 (without this patch) and have seen a few 
> 3-8% improvements in SPEC and a 100+% improvement in leslie3d.
> There were a couple of additional failures in SPEC that we have yet to 
> inspect but AFAICT no issue with respect to bitcode/assembly changes.

Hi @mnadeem, thanks for this patch. I'm having some trouble reproducing the 
improvement on leslie3d. Can you share more information about your 
configuration? Which flags did you use?


Repository:
  rG LLVM Github Monorepo

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[PATCH] D142420: [Flang] Add support to use LTO specific pipelines

[Usman Nadeem via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG0fdfb65e2624: [Flang] Add support to use LTO specific 
pipelines (authored by mnadeem).
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Changed prior to commit:
  https://reviews.llvm.org/D142420?vs=501214=503918#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
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Files:
  clang/include/clang/Driver/Options.td
  clang/lib/Driver/ToolChains/Flang.cpp
  flang/include/flang/Frontend/CodeGenOptions.def
  flang/lib/Frontend/CompilerInvocation.cpp
  flang/lib/Frontend/FrontendActions.cpp
  flang/test/Driver/default-optimization-pipelines.f90
  flang/test/Driver/driver-help-hidden.f90
  flang/test/Driver/driver-help.f90
  flang/test/Driver/lto-bc.f90
  flang/test/Driver/lto-flags.f90

Index: flang/test/Driver/lto-flags.f90
===
--- /dev/null
+++ flang/test/Driver/lto-flags.f90
@@ -0,0 +1,32 @@
+! UNSUPPORTED: system-windows
+! RUN: %flang -### -S %s 2>&1 | FileCheck %s --check-prefix=NO-LTO
+! RUN: %flang -### -S -fno-lto %s 2>&1 | FileCheck %s --check-prefix=NO-LTO
+
+! Full LTO and aliases.
+! RUN: %flang -### -S -flto %s 2>&1 | FileCheck %s --check-prefix=FULL-LTO
+! RUN: %flang -### -S -flto=full %s 2>&1 | FileCheck %s --check-prefix=FULL-LTO
+! RUN: %flang -### -S -flto=auto %s 2>&1 | FileCheck %s --check-prefix=FULL-LTO
+! RUN: %flang -### -S -flto=jobserver %s 2>&1 | FileCheck %s --check-prefix=FULL-LTO
+
+! Also check linker plugin opt for Thin LTO
+! RUN: %flang -### -flto=thin %s 2>&1 | FileCheck %s --check-prefix=THIN-LTO
+
+! RUN: %flang -### -S -flto=somelto %s 2>&1 | FileCheck %s --check-prefix=ERROR
+
+! FC1 tests. Check that it does not crash.
+! RUN: %flang_fc1 -S %s -flto -o /dev/null
+! RUN: %flang_fc1 -S %s -flto=full -o /dev/null
+! RUN: %flang_fc1 -S %s -flto=thin -o /dev/null
+
+! NO-LTO: "-fc1"
+! NO-LTO-NOT: flto
+
+! FULL-LTO: "-fc1"
+! FULL-LTO-SAME: "-flto=full"
+
+! THIN-LTO: flang-new: warning: the option '-flto=thin' is a work in progress
+! THIN-LTO: "-fc1"
+! THIN-LTO-SAME: "-flto=thin"
+! THIN-LTO: "-plugin-opt=thinlto"
+
+! ERROR: error: unsupported argument 'somelto' to option '-flto=
Index: flang/test/Driver/lto-bc.f90
===
--- /dev/null
+++ flang/test/Driver/lto-bc.f90
@@ -0,0 +1,21 @@
+! Test that the output is LLVM bitcode for LTO and not a native objectfile by
+! disassembling it to LLVM IR.
+! Right now there is nothing special about it and it is similar to non-lto IR,
+! more work is needed to add things like module summaries.
+
+! RUN: %flang %s -c -o - | not llvm-dis -o %t
+! RUN: %flang_fc1 %s -emit-llvm-bc -o - | llvm-dis -o - | FileCheck %s
+
+! RUN: %flang -flto %s -c -o - | llvm-dis -o - | FileCheck %s
+! RUN: %flang -flto=thin %s -c -o - | llvm-dis -o - | FileCheck %s
+
+! CHECK: define void @_QQmain()
+! CHECK-NEXT:  ret void
+! CHECK-NEXT: }
+
+! CHECK-NOT: ^0 = module:
+! CHECK-NOT: ^1 = gv: (name:
+! CHECK-NOT: ^2 = flags:
+! CHECK-NOT: ^3 = blockcount:
+
+end program
Index: flang/test/Driver/driver-help.f90
===
--- flang/test/Driver/driver-help.f90
+++ flang/test/Driver/driver-help.f90
@@ -41,6 +41,8 @@
 ! HELP-NEXT:Specify where to find the compiled intrinsic modules
 ! HELP-NEXT: -flarge-sizes  Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! HELP-NEXT: -flogical-abbreviations Enable logical abbreviations
+! HELP-NEXT: -flto= Set LTO mode
+! HELP-NEXT: -flto Enable LTO in 'full' mode
 ! HELP-NEXT: -fno-automatic Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! HELP-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
 ! HELP-NEXT: -fno-integrated-as  Disable the integrated assembler
@@ -130,6 +132,8 @@
 ! HELP-FC1-NEXT:Specify where to find the compiled intrinsic modules
 ! HELP-FC1-NEXT: -flarge-sizes  Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! HELP-FC1-NEXT: -flogical-abbreviations Enable logical abbreviations
+! HELP-FC1-NEXT: -flto=   Set LTO mode
+! HELP-FC1-NEXT: -flto   Enable LTO in 'full' mode
 ! HELP-FC1-NEXT: -fno-analyzed-objects-for-unparse
 ! HELP-FC1-NEXT:Do not use the analyzed objects when unparsing
 ! HELP-FC1-NEXT: -fno-automatic Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
Index: flang/test/Driver/driver-help-hidden.f90
===
--- flang/test/Driver/driver-help-hidden.f90
+++ flang/test/Driver/driver-help-hidden.f90
@@ -43,6 +43,8 @@
 ! CHECK-NEXT: