https://github.com/sebpop updated
https://github.com/llvm/llvm-project/pull/142686
>From ff88172ea86363bd25f73fc78af1b8fca2cc4f3d Mon Sep 17 00:00:00 2001
From: Sebastian Pop <s...@nvidia.com>
Date: Thu, 22 May 2025 13:50:38 +0000
Subject: [PATCH] add -floop-fuse to clang and flang
---
clang/include/clang/Basic/CodeGenOptions.def | 1 +
clang/include/clang/Driver/Options.td | 4 ++++
clang/lib/CodeGen/BackendUtil.cpp | 2 ++
clang/lib/Driver/ToolChains/Clang.cpp | 1 +
clang/lib/Driver/ToolChains/CommonArgs.cpp | 2 +-
clang/lib/Driver/ToolChains/Flang.cpp | 2 ++
clang/lib/Frontend/CompilerInvocation.cpp | 6 ++++++
clang/test/Driver/clang_f_opts.c | 7 +++++++
flang/docs/ReleaseNotes.md | 1 +
flang/include/flang/Frontend/CodeGenOptions.def | 1 +
flang/lib/Frontend/CompilerInvocation.cpp | 3 +++
flang/lib/Frontend/FrontendActions.cpp | 1 +
flang/test/Driver/loop-fuse.f90 | 17 +++++++++++++++++
llvm/include/llvm/Passes/PassBuilder.h | 3 +++
llvm/lib/Passes/PassBuilderPipelines.cpp | 13 ++++++++++++-
15 files changed, 62 insertions(+), 2 deletions(-)
create mode 100644 flang/test/Driver/loop-fuse.f90
diff --git a/clang/include/clang/Basic/CodeGenOptions.def
b/clang/include/clang/Basic/CodeGenOptions.def
index aad4e107cbeb3..de40564bc280f 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -326,6 +326,7 @@ CODEGENOPT(TimeTrace , 1, 0) ///< Set when
-ftime-trace is enabled.
VALUE_CODEGENOPT(TimeTraceGranularity, 32, 500) ///< Minimum time granularity
(in microseconds),
///< traced by time profiler
CODEGENOPT(InterchangeLoops , 1, 0) ///< Run loop-interchange.
+CODEGENOPT(FuseLoops , 1, 0) ///< Run loop-fuse.
CODEGENOPT(UnrollLoops , 1, 0) ///< Control whether loops are unrolled.
CODEGENOPT(RerollLoops , 1, 0) ///< Control whether loops are rerolled.
CODEGENOPT(NoUseJumpTables , 1, 0) ///< Set when -fno-jump-tables is enabled.
diff --git a/clang/include/clang/Driver/Options.td
b/clang/include/clang/Driver/Options.td
index 5ca31c253ed8f..e5e2c0035e03f 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4189,6 +4189,10 @@ def floop_interchange : Flag<["-"],
"floop-interchange">, Group<f_Group>,
HelpText<"Enable the loop interchange pass">, Visibility<[ClangOption,
CC1Option, FlangOption, FC1Option]>;
def fno_loop_interchange: Flag<["-"], "fno-loop-interchange">, Group<f_Group>,
HelpText<"Disable the loop interchange pass">, Visibility<[ClangOption,
CC1Option, FlangOption, FC1Option]>;
+def floop_fuse : Flag<["-"], "floop-fuse">, Group<f_Group>,
+ HelpText<"Enable the loop fuse pass">, Visibility<[ClangOption, CC1Option,
FlangOption, FC1Option]>;
+def fno_loop_fuse: Flag<["-"], "fno-loop-fuse">, Group<f_Group>,
+ HelpText<"Disable the loop fuse pass">, Visibility<[ClangOption, CC1Option,
FlangOption, FC1Option]>;
def funroll_loops : Flag<["-"], "funroll-loops">, Group<f_Group>,
HelpText<"Turn on loop unroller">, Visibility<[ClangOption, CC1Option,
FlangOption, FC1Option]>;
def fno_unroll_loops : Flag<["-"], "fno-unroll-loops">, Group<f_Group>,
diff --git a/clang/lib/CodeGen/BackendUtil.cpp
b/clang/lib/CodeGen/BackendUtil.cpp
index cd5fc48c4a22b..539e413e8c86e 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -898,6 +898,7 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
PipelineTuningOptions PTO;
PTO.LoopUnrolling = CodeGenOpts.UnrollLoops;
PTO.LoopInterchange = CodeGenOpts.InterchangeLoops;
+ PTO.LoopFuse = CodeGenOpts.FuseLoops;
// For historical reasons, loop interleaving is set to mirror setting for
loop
// unrolling.
PTO.LoopInterleaving = CodeGenOpts.UnrollLoops;
@@ -1339,6 +1340,7 @@ runThinLTOBackend(CompilerInstance &CI,
ModuleSummaryIndex *CombinedIndex,
Conf.SampleProfile = std::move(SampleProfile);
Conf.PTO.LoopUnrolling = CGOpts.UnrollLoops;
Conf.PTO.LoopInterchange = CGOpts.InterchangeLoops;
+ Conf.PTO.LoopFuse = CGOpts.FuseLoops;
// For historical reasons, loop interleaving is set to mirror setting for
loop
// unrolling.
Conf.PTO.LoopInterleaving = CGOpts.UnrollLoops;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp
b/clang/lib/Driver/ToolChains/Clang.cpp
index 13842b8cc2870..f3713e12cb5ef 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7030,6 +7030,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction
&JA,
options::OPT_fno_unroll_loops);
Args.AddLastArg(CmdArgs, options::OPT_floop_interchange,
options::OPT_fno_loop_interchange);
+ Args.AddLastArg(CmdArgs, options::OPT_floop_fuse,
options::OPT_fno_loop_fuse);
Args.AddLastArg(CmdArgs, options::OPT_fstrict_flex_arrays_EQ);
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 937ee09cac7cc..4217b48a56b05 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -3157,7 +3157,7 @@ void tools::handleVectorizeSLPArgs(const ArgList &Args,
void tools::handleInterchangeLoopsArgs(const ArgList &Args,
ArgStringList &CmdArgs) {
- // FIXME: instead of relying on shouldEnableVectorizerAtOLevel, we may want
to
+ // FIXME: Instead of relying on shouldEnableVectorizerAtOLevel, we may want
to
// implement a separate function to infer loop interchange from opt level.
// For now, enable loop-interchange at the same opt levels as loop-vectorize.
bool EnableInterchange = shouldEnableVectorizerAtOLevel(Args, false);
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp
b/clang/lib/Driver/ToolChains/Flang.cpp
index dcc46469df3e9..f34a58cab3ff3 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -151,6 +151,8 @@ void Flang::addCodegenOptions(const ArgList &Args,
!stackArrays->getOption().matches(options::OPT_fno_stack_arrays))
CmdArgs.push_back("-fstack-arrays");
+ Args.AddLastArg(CmdArgs, options::OPT_floop_fuse,
options::OPT_fno_loop_fuse);
+
handleInterchangeLoopsArgs(Args, CmdArgs);
handleVectorizeLoopsArgs(Args, CmdArgs);
handleVectorizeSLPArgs(Args, CmdArgs);
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp
b/clang/lib/Frontend/CompilerInvocation.cpp
index 2c02719121c73..582795956485e 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1648,6 +1648,11 @@ void CompilerInvocationBase::GenerateCodeGenArgs(const
CodeGenOptions &Opts,
else
GenerateArg(Consumer, OPT_fno_loop_interchange);
+ if (Opts.FuseLoops)
+ GenerateArg(Consumer, OPT_floop_fuse);
+ else
+ GenerateArg(Consumer, OPT_fno_loop_fuse);
+
if (!Opts.BinutilsVersion.empty())
GenerateArg(Consumer, OPT_fbinutils_version_EQ, Opts.BinutilsVersion);
@@ -1963,6 +1968,7 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions
&Opts, ArgList &Args,
(Opts.OptimizationLevel > 1));
Opts.InterchangeLoops =
Args.hasFlag(OPT_floop_interchange, OPT_fno_loop_interchange, false);
+ Opts.FuseLoops = Args.hasFlag(OPT_floop_fuse, OPT_fno_loop_fuse, false);
Opts.BinutilsVersion =
std::string(Args.getLastArgValue(OPT_fbinutils_version_EQ));
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index ee7ded265769b..204d5e338190f 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -52,6 +52,13 @@
// CHECK-INTERCHANGE-LOOPS: "-floop-interchange"
// CHECK-NO-INTERCHANGE-LOOPS: "-fno-loop-interchange"
+// RUN: %clang -### -S -floop-fuse %s 2>&1 | FileCheck
-check-prefix=CHECK-FUSE-LOOPS %s
+// RUN: %clang -### -S -fno-loop-fuse %s 2>&1 | FileCheck
-check-prefix=CHECK-NO-FUSE-LOOPS %s
+// RUN: %clang -### -S -fno-loop-fuse -floop-fuse %s 2>&1 | FileCheck
-check-prefix=CHECK-FUSE-LOOPS %s
+// RUN: %clang -### -S -floop-fuse -fno-loop-fuse %s 2>&1 | FileCheck
-check-prefix=CHECK-NO-FUSE-LOOPS %s
+// CHECK-FUSE-LOOPS: "-floop-fuse"
+// CHECK-NO-FUSE-LOOPS: "-fno-loop-fuse"
+
// RUN: %clang -### -S -fprofile-sample-accurate %s 2>&1 | FileCheck
-check-prefix=CHECK-PROFILE-SAMPLE-ACCURATE %s
// CHECK-PROFILE-SAMPLE-ACCURATE: "-fprofile-sample-accurate"
diff --git a/flang/docs/ReleaseNotes.md b/flang/docs/ReleaseNotes.md
index 36be369595ffd..33795b7d1a55a 100644
--- a/flang/docs/ReleaseNotes.md
+++ b/flang/docs/ReleaseNotes.md
@@ -34,6 +34,7 @@ page](https://llvm.org/releases/).
* -floop-interchange is now recognized by flang.
* -floop-interchange is enabled by default at -O2 and above.
+* -floop-fuse is now recognized by flang.
## Windows Support
diff --git a/flang/include/flang/Frontend/CodeGenOptions.def
b/flang/include/flang/Frontend/CodeGenOptions.def
index a697872836569..85bec620b54ba 100644
--- a/flang/include/flang/Frontend/CodeGenOptions.def
+++ b/flang/include/flang/Frontend/CodeGenOptions.def
@@ -36,6 +36,7 @@ CODEGENOPT(StackArrays, 1, 0) ///< -fstack-arrays (enable the
stack-arrays pass)
CODEGENOPT(VectorizeLoop, 1, 0) ///< Enable loop vectorization.
CODEGENOPT(VectorizeSLP, 1, 0) ///< Enable SLP vectorization.
CODEGENOPT(InterchangeLoops, 1, 0) ///< Enable loop interchange.
+CODEGENOPT(FuseLoops, 1, 0) ///< Enable loop fuse.
CODEGENOPT(LoopVersioning, 1, 0) ///< Enable loop versioning.
CODEGENOPT(UnrollLoops, 1, 0) ///< Enable loop unrolling
CODEGENOPT(AliasAnalysis, 1, 0) ///< Enable alias analysis pass
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp
b/flang/lib/Frontend/CompilerInvocation.cpp
index 90a002929eff0..c2b63819e9f77 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -273,6 +273,9 @@ static void
parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
if (args.getLastArg(clang::driver::options::OPT_floop_interchange))
opts.InterchangeLoops = 1;
+ if (args.getLastArg(clang::driver::options::OPT_floop_fuse))
+ opts.FuseLoops = 1;
+
if (args.getLastArg(clang::driver::options::OPT_vectorize_loops))
opts.VectorizeLoop = 1;
diff --git a/flang/lib/Frontend/FrontendActions.cpp
b/flang/lib/Frontend/FrontendActions.cpp
index 012d0fdfe645f..dc56cbe5c85bc 100644
--- a/flang/lib/Frontend/FrontendActions.cpp
+++ b/flang/lib/Frontend/FrontendActions.cpp
@@ -925,6 +925,7 @@ void
CodeGenAction::runOptimizationPipeline(llvm::raw_pwrite_stream &os) {
si.getTimePasses().setOutStream(ci.getTimingStreamLLVM());
pto.LoopUnrolling = opts.UnrollLoops;
pto.LoopInterchange = opts.InterchangeLoops;
+ pto.LoopFuse = opts.FuseLoops;
pto.LoopInterleaving = opts.UnrollLoops;
pto.LoopVectorization = opts.VectorizeLoop;
pto.SLPVectorization = opts.VectorizeSLP;
diff --git a/flang/test/Driver/loop-fuse.f90 b/flang/test/Driver/loop-fuse.f90
new file mode 100644
index 0000000000000..240d00fdb62d7
--- /dev/null
+++ b/flang/test/Driver/loop-fuse.f90
@@ -0,0 +1,17 @@
+! RUN: %flang -### -S -floop-fuse %s 2>&1 | FileCheck
-check-prefix=CHECK-LOOP-FUSE %s
+! RUN: %flang -### -S -fno-loop-fuse %s 2>&1 | FileCheck
-check-prefix=CHECK-NO-LOOP-FUSE %s
+! RUN: %flang -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-LOOP-FUSE
%s
+! RUN: %flang -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-LOOP-FUSE
%s
+! RUN: %flang -### -S -O2 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-LOOP-FUSE
%s
+! RUN: %flang -### -S -O3 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-LOOP-FUSE
%s
+! RUN: %flang -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECK-NO-LOOP-FUSE
%s
+! RUN: %flang -### -S -Oz %s 2>&1 | FileCheck -check-prefix=CHECK-NO-LOOP-FUSE
%s
+! CHECK-LOOP-FUSE: "-floop-fuse"
+! CHECK-NO-LOOP-FUSE-NOT: "-floop-fuse"
+! RUN: %flang_fc1 -emit-llvm -O2 -floop-fuse -mllvm -print-pipeline-passes -o
/dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-LOOP-FUSE-PASS %s
+! RUN: %flang_fc1 -emit-llvm -O2 -fno-loop-fuse -mllvm -print-pipeline-passes
-o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-NO-LOOP-FUSE-PASS %s
+! CHECK-LOOP-FUSE-PASS: loop-fusion
+! CHECK-NO-LOOP-FUSE-PASS-NOT: loop-fusion
+
+program test
+end program
diff --git a/llvm/include/llvm/Passes/PassBuilder.h
b/llvm/include/llvm/Passes/PassBuilder.h
index 51ccaa53447d7..287a57c7d4a7d 100644
--- a/llvm/include/llvm/Passes/PassBuilder.h
+++ b/llvm/include/llvm/Passes/PassBuilder.h
@@ -64,6 +64,9 @@ class PipelineTuningOptions {
/// false.
bool LoopInterchange;
+ /// Tuning option to enable/disable loop fuse. Its default value is false.
+ bool LoopFuse;
+
/// Tuning option to forget all SCEV loops in LoopUnroll. Its default value
/// is that of the flag: `-forget-scev-loop-unroll`.
bool ForgetAllSCEVInLoopUnroll;
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp
b/llvm/lib/Passes/PassBuilderPipelines.cpp
index f3654600c5abb..aaf43a9b535e9 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -104,6 +104,7 @@
#include "llvm/Transforms/Scalar/LoopDeletion.h"
#include "llvm/Transforms/Scalar/LoopDistribute.h"
#include "llvm/Transforms/Scalar/LoopFlatten.h"
+#include "llvm/Transforms/Scalar/LoopFuse.h"
#include "llvm/Transforms/Scalar/LoopIdiomRecognize.h"
#include "llvm/Transforms/Scalar/LoopInstSimplify.h"
#include "llvm/Transforms/Scalar/LoopInterchange.h"
@@ -205,6 +206,10 @@ static cl::opt<bool>
EnableLoopInterchange("enable-loopinterchange", cl::init(false),
cl::Hidden,
cl::desc("Enable the LoopInterchange Pass"));
+static cl::opt<bool> EnableLoopFuse("enable-loopfuse", cl::init(false),
+ cl::Hidden,
+ cl::desc("Enable the LoopFuse Pass"));
+
static cl::opt<bool> EnableUnrollAndJam("enable-unroll-and-jam",
cl::init(false), cl::Hidden,
cl::desc("Enable Unroll And Jam
Pass"));
@@ -314,6 +319,7 @@ PipelineTuningOptions::PipelineTuningOptions() {
SLPVectorization = false;
LoopUnrolling = true;
LoopInterchange = EnableLoopInterchange;
+ LoopFuse = EnableLoopFuse;
ForgetAllSCEVInLoopUnroll = ForgetSCEVInLoopUnroll;
LicmMssaOptCap = SetLicmMssaOptCap;
LicmMssaNoAccForPromotionCap = SetLicmMssaNoAccForPromotionCap;
@@ -518,6 +524,9 @@
PassBuilder::buildO1FunctionSimplificationPipeline(OptimizationLevel Level,
invokeLoopOptimizerEndEPCallbacks(LPM2, Level);
+ if (PTO.LoopFuse)
+ FPM.addPass(LoopFusePass());
+
FPM.addPass(createFunctionToLoopPassAdaptor(std::move(LPM1),
/*UseMemorySSA=*/true,
/*UseBlockFrequencyInfo=*/true));
@@ -709,6 +718,9 @@
PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
invokeLoopOptimizerEndEPCallbacks(LPM2, Level);
+ if (PTO.LoopFuse)
+ FPM.addPass(LoopFusePass());
+
FPM.addPass(createFunctionToLoopPassAdaptor(std::move(LPM1),
/*UseMemorySSA=*/true,
/*UseBlockFrequencyInfo=*/true));
@@ -2112,7 +2124,6 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel
Level,
LPM.addPass(LoopFlattenPass());
LPM.addPass(IndVarSimplifyPass());
LPM.addPass(LoopDeletionPass());
- // FIXME: Add loop interchange.
// Unroll small loops and perform peeling.
LPM.addPass(LoopFullUnrollPass(Level.getSpeedupLevel(),
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