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[RISCV] Enable merging of external globals by default (#117880)
This follows up #115495 by enabling merging of external globals by default, which had been left as a next step in order to make the previous change more incremental and so we can more easily narrow down on any identified regressions. Enabling merging of external globals matches what Arm does (for non mach-o targets), though AArch64 doesn't as there were [some concerns](https://reviews.llvm.org/D61947) it might cause regressions in some cases. See #117880 for benchmark figures and discussion.
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6 files changed

+19
-29
lines changed

6 files changed

+19
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lines changed

‎llvm/lib/Target/RISCV/RISCVTargetMachine.cpp‎

Lines changed: 1 addition & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -51,13 +51,6 @@ static cl::opt<cl::boolOrDefault>
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EnableGlobalMerge("riscv-enable-global-merge", cl::Hidden,
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cl::desc("Enable the global merge pass"));
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54-
static cl::opt<bool> ForceEnableGlobalMergeExternalGlobals(
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"riscv-force-enable-global-merge-external-globals", cl::Hidden,
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cl::init(false),
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cl::desc(
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"If the global merge pass is enabled, force enable global merging of "
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"external globals (overriding any logic that might disable it)"));
60-
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static cl::opt<bool>
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EnableMachineCombiner("riscv-enable-machine-combiner",
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cl::desc("Enable the machine combiner pass"),
@@ -494,8 +487,7 @@ bool RISCVPassConfig::addPreISel() {
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// Investigating and addressing both items are TODO.
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addPass(createGlobalMergePass(TM, /* MaxOffset */ 2047,
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/* OnlyOptimizeForSize */ false,
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/* MergeExternalByDefault */
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ForceEnableGlobalMergeExternalGlobals));
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/* MergeExternalByDefault */ true));
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}
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return false;

‎llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,7 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
2-
; RUN: llc -mtriple=riscv64 -riscv-force-enable-global-merge-external-globals \
3-
; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
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; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=0 \
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; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
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; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
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; RUN: | FileCheck %s -check-prefix=SMALL-DATA
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; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=0 -verify-machineinstrs < %s \
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; RUN: | FileCheck %s -check-prefix=MINSIZE
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@ig1 = internal global i32 0, align 4

‎llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,7 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc -mtriple=riscv32 -riscv-force-enable-global-merge-external-globals \
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; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
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; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=5 \
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; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
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; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
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; RUN: | FileCheck %s -check-prefix=SMALL-DATA
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; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=5 -verify-machineinstrs < %s \
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; RUN: | FileCheck %s -check-prefix=MINSIZE
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@ig1 = internal global i32 0, align 4

‎llvm/test/CodeGen/RISCV/global-merge-minsize.ll‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,8 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
2-
; RUN: llc -mtriple=riscv32 -riscv-force-enable-global-merge-external-globals \
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; RUN: llc -mtriple=riscv32 \
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; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32
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; RUN: llc -mtriple=riscv32 -global-merge-min-data-size=5 \
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; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32-MINSIZE
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; RUN: -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32-MINSIZE
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@ig1 = internal global i32 0, align 4
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@ig2 = internal global i32 0, align 4

‎llvm/test/CodeGen/RISCV/global-merge-offset.ll‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,12 +1,12 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv32 \
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; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
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; RUN: -verify-machineinstrs | FileCheck %s
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; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv64 \
5-
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
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; RUN: -verify-machineinstrs | FileCheck %s
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; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv32 \
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; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
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; RUN: -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
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; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv64 \
9-
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
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; RUN: -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
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; This test demonstrates that the MaxOffset is set correctly for RISC-V by
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; constructing an input that is at the limit and comparing.

‎llvm/test/CodeGen/RISCV/global-merge.ll‎

Lines changed: 6 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,11 @@
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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
2-
; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s | FileCheck %s
3-
; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s | FileCheck %s
4-
; RUN: llc -mtriple=riscv32 \
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; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
2+
; RUN: llc -mtriple=riscv32 -global-merge-on-external=false \
3+
; RUN: -verify-machineinstrs < %s | FileCheck %s
4+
; RUN: llc -mtriple=riscv64 -global-merge-on-external=false \
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; RUN: -verify-machineinstrs < %s | FileCheck %s
6+
; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
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; RUN: | FileCheck -check-prefix=CHECK-WEXTERN %s
7-
; RUN: llc -mtriple=riscv64 \
8-
; RUN: -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
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; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
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; RUN: | FileCheck -check-prefix=CHECK-WEXTERN %s
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1111
@ig1 = internal global i32 0, align 4

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