[llvm] a194438 - [CodeGen] Add -align-loops
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 4 12:45:23 PDT 2021
Author: Fangrui Song
Date: 2021-08-04T12:45:18-07:00
New Revision: a1944386156dbbfae15dfc606a3728e08ac92cfe
URL: https://github.com/llvm/llvm-project/commit/a1944386156dbbfae15dfc606a3728e08ac92cfe
DIFF: https://github.com/llvm/llvm-project/commit/a1944386156dbbfae15dfc606a3728e08ac92cfe.diff
LOG: [CodeGen] Add -align-loops
to `lib/CodeGen/CommandFlags.cpp`. It can replace
-x86-experimental-pref-loop-alignment=.
The loop alignment is only used by MachineBlockPlacement.
The implementation uses a new `llvm::TargetOptions` for now, as
an IR function attribute/module flags metadata may be overkill.
This is the llvm part of D106701.
Added:
llvm/test/CodeGen/RISCV/align-loops.ll
Modified:
llvm/include/llvm/CodeGen/CommandFlags.h
llvm/include/llvm/CodeGen/TargetLowering.h
llvm/include/llvm/Target/TargetOptions.h
llvm/lib/CodeGen/CommandFlags.cpp
llvm/lib/CodeGen/TargetLoweringBase.cpp
llvm/test/CodeGen/X86/innermost-loop-alignment.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/CodeGen/CommandFlags.h b/llvm/include/llvm/CodeGen/CommandFlags.h
index 5a43517562975..7ae951e3dfa8b 100644
--- a/llvm/include/llvm/CodeGen/CommandFlags.h
+++ b/llvm/include/llvm/CodeGen/CommandFlags.h
@@ -138,6 +138,8 @@ bool getXRayOmitFunctionIndex();
bool getDebugStrictDwarf();
+unsigned getAlignLoops();
+
/// Create this object with static storage to register codegen-related command
/// line options.
struct RegisterCodeGenFlags {
diff --git a/llvm/include/llvm/CodeGen/TargetLowering.h b/llvm/include/llvm/CodeGen/TargetLowering.h
index a4955e2a973a0..69508d85cc33f 100644
--- a/llvm/include/llvm/CodeGen/TargetLowering.h
+++ b/llvm/include/llvm/CodeGen/TargetLowering.h
@@ -1768,9 +1768,7 @@ class TargetLoweringBase {
Align getPrefFunctionAlignment() const { return PrefFunctionAlignment; }
/// Return the preferred loop alignment.
- virtual Align getPrefLoopAlignment(MachineLoop *ML = nullptr) const {
- return PrefLoopAlignment;
- }
+ virtual Align getPrefLoopAlignment(MachineLoop *ML = nullptr) const;
/// Should loops be aligned even when the function is marked OptSize (but not
/// MinSize).
diff --git a/llvm/include/llvm/Target/TargetOptions.h b/llvm/include/llvm/Target/TargetOptions.h
index e5bea9041479c..20c715ea4d32a 100644
--- a/llvm/include/llvm/Target/TargetOptions.h
+++ b/llvm/include/llvm/Target/TargetOptions.h
@@ -328,6 +328,9 @@ namespace llvm {
/// passed on the command line.
std::string StackUsageOutput;
+ /// If greater than 0, override TargetLoweringBase::PrefLoopAlignment.
+ unsigned LoopAlignment = 0;
+
/// FloatABIType - This setting is set by -float-abi=xxx option is specfied
/// on the command line. This setting may either be Default, Soft, or Hard.
/// Default selects the target's default behavior. Soft selects the ABI for
diff --git a/llvm/lib/CodeGen/CommandFlags.cpp b/llvm/lib/CodeGen/CommandFlags.cpp
index f3cba6225107f..e5f5da5cc212c 100644
--- a/llvm/lib/CodeGen/CommandFlags.cpp
+++ b/llvm/lib/CodeGen/CommandFlags.cpp
@@ -94,6 +94,7 @@ CGOPT(bool, ValueTrackingVariableLocations)
CGOPT(bool, ForceDwarfFrameSection)
CGOPT(bool, XRayOmitFunctionIndex)
CGOPT(bool, DebugStrictDwarf)
+CGOPT(unsigned, AlignLoops)
codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
#define CGBINDOPT(NAME) \
@@ -452,6 +453,10 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
"strict-dwarf", cl::desc("use strict dwarf"), cl::init(false));
CGBINDOPT(DebugStrictDwarf);
+ static cl::opt<unsigned> AlignLoops("align-loops",
+ cl::desc("Default alignment for loops"));
+ CGBINDOPT(AlignLoops);
+
#undef CGBINDOPT
mc::RegisterMCTargetOptionsFlags();
@@ -527,6 +532,7 @@ codegen::InitTargetOptionsFromCodeGenFlags(const Triple &TheTriple) {
Options.ForceDwarfFrameSection = getForceDwarfFrameSection();
Options.XRayOmitFunctionIndex = getXRayOmitFunctionIndex();
Options.DebugStrictDwarf = getDebugStrictDwarf();
+ Options.LoopAlignment = getAlignLoops();
Options.MCOptions = mc::InitMCTargetOptionsFromFlags();
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 842280ab953e3..cfbbba69f5c42 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -52,6 +52,7 @@
#include "llvm/Support/MachineValueType.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/Utils/SizeOpts.h"
#include <algorithm>
#include <cassert>
@@ -2018,6 +2019,12 @@ bool TargetLoweringBase::isJumpTableRelative() const {
return getTargetMachine().isPositionIndependent();
}
+Align TargetLoweringBase::getPrefLoopAlignment(MachineLoop *ML) const {
+ if (TM.Options.LoopAlignment)
+ return Align(TM.Options.LoopAlignment);
+ return PrefLoopAlignment;
+}
+
//===----------------------------------------------------------------------===//
// Reciprocal Estimates
//===----------------------------------------------------------------------===//
diff --git a/llvm/test/CodeGen/RISCV/align-loops.ll b/llvm/test/CodeGen/RISCV/align-loops.ll
new file mode 100644
index 0000000000000..efa03992b6277
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/align-loops.ll
@@ -0,0 +1,44 @@
+; RUN: llc < %s -mtriple=riscv64 | FileCheck %s
+; RUN: llc < %s -mtriple=riscv64 -align-loops=16 | FileCheck %s -check-prefix=ALIGN_16
+; RUN: llc < %s -mtriple=riscv64 -align-loops=32 | FileCheck %s -check-prefix=ALIGN_32
+
+declare void @foo()
+
+define void @test(i32 %n, i32 %m) nounwind {
+; CHECK-LABEL: test:
+; CHECK-NOT: .p2align
+; CHECK: ret
+
+; ALIGN_16-LABEL: test:
+; ALIGN_16: .p2align 4{{$}}
+; ALIGN_16-NEXT: .LBB0_1: # %outer
+; ALIGN_16: .p2align 4{{$}}
+; ALIGN_16-NEXT: .LBB0_2: # %inner
+
+; ALIGN_32-LABEL: test:
+; ALIGN_32: .p2align 5{{$}}
+; ALIGN_32-NEXT: .LBB0_1: # %outer
+; ALIGN_32: .p2align 5{{$}}
+; ALIGN_32-NEXT: .LBB0_2: # %inner
+entry:
+ br label %outer
+
+outer:
+ %outer.iv = phi i32 [0, %entry], [%outer.iv.next, %outer_bb]
+ br label %inner
+
+inner:
+ %inner.iv = phi i32 [0, %outer], [%inner.iv.next, %inner]
+ call void @foo()
+ %inner.iv.next = add i32 %inner.iv, 1
+ %inner.cond = icmp ne i32 %inner.iv.next, %m
+ br i1 %inner.cond, label %inner, label %outer_bb
+
+outer_bb:
+ %outer.iv.next = add i32 %outer.iv, 1
+ %outer.cond = icmp ne i32 %outer.iv.next, %n
+ br i1 %outer.cond, label %outer, label %exit
+
+exit:
+ ret void
+}
diff --git a/llvm/test/CodeGen/X86/innermost-loop-alignment.ll b/llvm/test/CodeGen/X86/innermost-loop-alignment.ll
index a97e9a86a7556..113d5bffe983b 100644
--- a/llvm/test/CodeGen/X86/innermost-loop-alignment.ll
+++ b/llvm/test/CodeGen/X86/innermost-loop-alignment.ll
@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=i686-pc-linux-gnu | FileCheck %s -check-prefix=DEFAULT
; RUN: llc < %s -mtriple=i686-pc-linux-gnu -x86-experimental-pref-innermost-loop-alignment=5 | FileCheck %s -check-prefix=ALIGN32
-; RUN: llc < %s -mtriple=i686-pc-linux-gnu -x86-experimental-pref-loop-alignment=5 -x86-experimental-pref-innermost-loop-alignment=6 | FileCheck %s -check-prefix=ALIGN64
+; RUN: llc < %s -mtriple=i686-pc-linux-gnu -align-loops=32 -x86-experimental-pref-innermost-loop-alignment=6 | FileCheck %s -check-prefix=ALIGN64
declare void @foo()
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