[llvm] [RISCV] Enable global merging by default (PR #115495)
Alex Bradbury via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 13 06:36:33 PST 2024
https://github.com/asb updated https://github.com/llvm/llvm-project/pull/115495
>From 269df4cd7681063243bb05b23dbf50fcc394338b Mon Sep 17 00:00:00 2001
From: Alex Bradbury <asb at igalia.com>
Date: Fri, 8 Nov 2024 14:00:06 +0000
Subject: [PATCH 1/2] [RISCV] When using global merging, don't enable merging
of external globals by default
AArch64 left this disabled after seeing some cases of slightly worse
codegen that weren't tracked down, so I suggest as a path to
incrementally moving towards enable globals merging we follow suit, and
evaluate turning on later.
This patch disables merging of external globals, but also adds a flag to
override that. This reduces churn in test cases, simplifies benchmarking
runs, and this flag can be removed later.
---
llvm/lib/Target/RISCV/RISCVTargetMachine.cpp | 10 ++++++++-
.../global-merge-minsize-smalldata-nonzero.ll | 7 +++---
.../global-merge-minsize-smalldata-zero.ll | 7 +++---
.../CodeGen/RISCV/global-merge-minsize.ll | 6 ++---
.../test/CodeGen/RISCV/global-merge-offset.ll | 8 +++----
llvm/test/CodeGen/RISCV/global-merge.ll | 22 +++++++++++++++++--
6 files changed, 44 insertions(+), 16 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index a5afbcfd79710f..6a97755c279a29 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -53,6 +53,13 @@ static cl::opt<cl::boolOrDefault>
EnableGlobalMerge("riscv-enable-global-merge", cl::Hidden,
cl::desc("Enable the global merge pass"));
+static cl::opt<bool> ForceEnableGlobalMergeExternalGlobals(
+ "riscv-force-enable-global-merge-external-globals", cl::Hidden,
+ cl::init(false),
+ cl::desc(
+ "If the global merge pass is enabled, force enable global merging of "
+ "external globals (overriding any logic that might disable it)"));
+
static cl::opt<bool>
EnableMachineCombiner("riscv-enable-machine-combiner",
cl::desc("Enable the machine combiner pass"),
@@ -472,7 +479,8 @@ bool RISCVPassConfig::addPreISel() {
if (EnableGlobalMerge == cl::BOU_TRUE) {
addPass(createGlobalMergePass(TM, /* MaxOffset */ 2047,
/* OnlyOptimizeForSize */ false,
- /* MergeExternalByDefault */ true));
+ /* MergeExternalByDefault */
+ ForceEnableGlobalMergeExternalGlobals));
}
return false;
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
index c5471389302124..39c677ac20b3a5 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
@@ -1,8 +1,9 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -verify-machineinstrs < %s \
-; RUN: | FileCheck %s -check-prefix=SMALL-DATA
+; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -global-merge-min-data-size=0 \
-; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=MINSIZE
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
+; RUN: | FileCheck %s -check-prefix=MINSIZE
@ig1 = internal global i32 0, align 4
@ig2 = internal global i32 0, align 4
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
index 8e4d72af00ebce..d2b714577db9a8 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
@@ -1,8 +1,9 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -verify-machineinstrs < %s \
-; RUN: | FileCheck %s -check-prefix=SMALL-DATA
+; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -global-merge-min-data-size=5 \
-; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=MINSIZE
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
+; RUN: | FileCheck %s -check-prefix=MINSIZE
@ig1 = internal global i32 0, align 4
@ig2 = internal global i32 0, align 4
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
index e405425832acbb..696d163bdcb2c4 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
@@ -1,8 +1,8 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -verify-machineinstrs < %s \
-; RUN: | FileCheck %s -check-prefix=RV32
+; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32
; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -global-merge-min-data-size=5 \
-; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32-MINSIZE
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32-MINSIZE
@ig1 = internal global i32 0, align 4
@ig2 = internal global i32 0, align 4
diff --git a/llvm/test/CodeGen/RISCV/global-merge-offset.ll b/llvm/test/CodeGen/RISCV/global-merge-offset.ll
index 13afcba181719e..0c0881ddf28737 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-offset.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-offset.ll
@@ -1,12 +1,12 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv32 -riscv-enable-global-merge \
-; RUN: -verify-machineinstrs | FileCheck %s
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv64 -riscv-enable-global-merge \
-; RUN: -verify-machineinstrs | FileCheck %s
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv32 -riscv-enable-global-merge \
-; RUN: -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv64 -riscv-enable-global-merge \
-; RUN: -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
; This test demonstrates that the MaxOffset is set correctly for RISC-V by
; constructing an input that is at the limit and comparing.
diff --git a/llvm/test/CodeGen/RISCV/global-merge.ll b/llvm/test/CodeGen/RISCV/global-merge.ll
index 20379ee2e7dacd..633ba719c6a305 100644
--- a/llvm/test/CodeGen/RISCV/global-merge.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge.ll
@@ -3,6 +3,12 @@
; RUN: | FileCheck %s
; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -verify-machineinstrs < %s \
; RUN: | FileCheck %s
+; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge \
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
+; RUN: | FileCheck -check-prefix=CHECK-WEXTERN %s
+; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge \
+; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
+; RUN: | FileCheck -check-prefix=CHECK-WEXTERN %s
@ig1 = internal global i32 0, align 4
@ig2 = internal global i32 0, align 4
@@ -21,9 +27,21 @@ define void @f1(i32 %a) nounwind {
; CHECK-NEXT: sw a0, %lo(.L_MergedGlobals)(a1)
; CHECK-NEXT: addi a1, a1, %lo(.L_MergedGlobals)
; CHECK-NEXT: sw a0, 4(a1)
-; CHECK-NEXT: sw a0, 8(a1)
-; CHECK-NEXT: sw a0, 12(a1)
+; CHECK-NEXT: lui a1, %hi(eg1)
+; CHECK-NEXT: sw a0, %lo(eg1)(a1)
+; CHECK-NEXT: lui a1, %hi(eg2)
+; CHECK-NEXT: sw a0, %lo(eg2)(a1)
; CHECK-NEXT: ret
+;
+; CHECK-WEXTERN-LABEL: f1:
+; CHECK-WEXTERN: # %bb.0:
+; CHECK-WEXTERN-NEXT: lui a1, %hi(.L_MergedGlobals)
+; CHECK-WEXTERN-NEXT: sw a0, %lo(.L_MergedGlobals)(a1)
+; CHECK-WEXTERN-NEXT: addi a1, a1, %lo(.L_MergedGlobals)
+; CHECK-WEXTERN-NEXT: sw a0, 4(a1)
+; CHECK-WEXTERN-NEXT: sw a0, 8(a1)
+; CHECK-WEXTERN-NEXT: sw a0, 12(a1)
+; CHECK-WEXTERN-NEXT: ret
store i32 %a, ptr @ig1, align 4
store i32 %a, ptr @ig2, align 4
store i32 %a, ptr @eg1, align 4
>From fbeca728cac58f40e7d33d1bc5cbfade52ff8354 Mon Sep 17 00:00:00 2001
From: Alex Bradbury <asb at igalia.com>
Date: Fri, 8 Nov 2024 14:57:35 +0000
Subject: [PATCH 2/2] [RISCV] Enable global merging by default
Stacks on top of <https://github.com/llvm/llvm-project/pull/115484>.
>From the discussion at the round-table at the RISC-V Summit it was clear
people see cases where global merging would help. So the direction of
enabling it by default and iteratively working to enable it in more
cases or to improve the heuristics seems sensible. This patch tries to
make a minimal step in that direction.
---
llvm/lib/Target/RISCV/RISCVTargetMachine.cpp | 8 +++++++-
llvm/test/CodeGen/RISCV/O3-pipeline.ll | 1 +
.../RISCV/global-merge-minsize-smalldata-nonzero.ll | 4 ++--
.../RISCV/global-merge-minsize-smalldata-zero.ll | 4 ++--
llvm/test/CodeGen/RISCV/global-merge-minsize.ll | 4 ++--
llvm/test/CodeGen/RISCV/global-merge-offset.ll | 8 ++++----
llvm/test/CodeGen/RISCV/global-merge.ll | 10 ++++------
7 files changed, 22 insertions(+), 17 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 6a97755c279a29..4fc185525d8d25 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -476,7 +476,13 @@ bool RISCVPassConfig::addPreISel() {
addPass(createBarrierNoopPass());
}
- if (EnableGlobalMerge == cl::BOU_TRUE) {
+ if ((TM->getOptLevel() != CodeGenOptLevel::None &&
+ EnableGlobalMerge == cl::BOU_UNSET) ||
+ EnableGlobalMerge == cl::BOU_TRUE) {
+ // FIXME: Like AArch64, we disable extern global merging by default due to
+ // concerns it might regress some workloads. Unlike AArch64, we don't
+ // currently support enabling the pass in an "OnlyOptimizeForSize" mode.
+ // Investigating and addressing both items are TODO.
addPass(createGlobalMergePass(TM, /* MaxOffset */ 2047,
/* OnlyOptimizeForSize */ false,
/* MergeExternalByDefault */
diff --git a/llvm/test/CodeGen/RISCV/O3-pipeline.ll b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
index a74c842c595526..8fd9ae98503665 100644
--- a/llvm/test/CodeGen/RISCV/O3-pipeline.ll
+++ b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
@@ -74,6 +74,7 @@
; CHECK-NEXT: Exception handling preparation
; CHECK-NEXT: A No-Op Barrier Pass
; CHECK-NEXT: FunctionPass Manager
+; CHECK-NEXT: Merge internal globals
; CHECK-NEXT: Dominator Tree Construction
; CHECK-NEXT: Basic Alias Analysis (stateless AA impl)
; CHECK-NEXT: Function Alias Analysis Results
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
index 39c677ac20b3a5..156a34db827456 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: llc -mtriple=riscv64 -riscv-force-enable-global-merge-external-globals \
; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -global-merge-min-data-size=0 \
+; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=0 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
; RUN: | FileCheck %s -check-prefix=MINSIZE
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
index d2b714577db9a8..e41f14d394b7ca 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: llc -mtriple=riscv32 -riscv-force-enable-global-merge-external-globals \
; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -global-merge-min-data-size=5 \
+; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=5 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
; RUN: | FileCheck %s -check-prefix=MINSIZE
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
index 696d163bdcb2c4..1d65d9d1732ba3 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: llc -mtriple=riscv32 -riscv-force-enable-global-merge-external-globals \
; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -global-merge-min-data-size=5 \
+; RUN: llc -mtriple=riscv32 -global-merge-min-data-size=5 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32-MINSIZE
@ig1 = internal global i32 0, align 4
diff --git a/llvm/test/CodeGen/RISCV/global-merge-offset.ll b/llvm/test/CodeGen/RISCV/global-merge-offset.ll
index 0c0881ddf28737..bb8264ee438545 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-offset.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-offset.ll
@@ -1,11 +1,11 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv32 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv32 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
-; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv64 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv64 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
-; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv32 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv32 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
-; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv64 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv64 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
; This test demonstrates that the MaxOffset is set correctly for RISC-V by
diff --git a/llvm/test/CodeGen/RISCV/global-merge.ll b/llvm/test/CodeGen/RISCV/global-merge.ll
index 633ba719c6a305..8b4043ed476f77 100644
--- a/llvm/test/CodeGen/RISCV/global-merge.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge.ll
@@ -1,12 +1,10 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -verify-machineinstrs < %s \
-; RUN: | FileCheck %s
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -verify-machineinstrs < %s \
-; RUN: | FileCheck %s
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge \
+; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=riscv32 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
; RUN: | FileCheck -check-prefix=CHECK-WEXTERN %s
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge \
+; RUN: llc -mtriple=riscv64 \
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
; RUN: | FileCheck -check-prefix=CHECK-WEXTERN %s
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