[llvm] [RISCV] When using global merging, don't enable merging of external globals by default (PR #115484)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 8 06:05:28 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-risc-v
Author: Alex Bradbury (asb)
<details>
<summary>Changes</summary>
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.
A follow-on PR enables the globals merging pass by default (and as it's based on this commit, merging of external globals is disabled just as they are for AArch64).
---
Full diff: https://github.com/llvm/llvm-project/pull/115484.diff
6 Files Affected:
- (modified) llvm/lib/Target/RISCV/RISCVTargetMachine.cpp (+9-1)
- (modified) llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll (+4-3)
- (modified) llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll (+4-3)
- (modified) llvm/test/CodeGen/RISCV/global-merge-minsize.ll (+3-3)
- (modified) llvm/test/CodeGen/RISCV/global-merge-offset.ll (+4-4)
- (modified) llvm/test/CodeGen/RISCV/global-merge.ll (+20-2)
``````````diff
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
``````````
</details>
https://github.com/llvm/llvm-project/pull/115484
More information about the llvm-commits
mailing list