[llvm] r372443 - [GlobalISel] Defer setting HasCalls on MachineFrameInfo to selection time.
Amara Emerson via llvm-commits
llvm-commits at lists.llvm.org
Fri Sep 20 16:52:07 PDT 2019
Author: aemerson
Date: Fri Sep 20 16:52:07 2019
New Revision: 372443
URL: http://llvm.org/viewvc/llvm-project?rev=372443&view=rev
Log:
[GlobalISel] Defer setting HasCalls on MachineFrameInfo to selection time.
We currently always set the HasCalls on MFI during translation and legalization if
we're handling a call or legalizing to a libcall. However, if that call is later
optimized to a tail call then we don't need the flag. The flag being set to true
causes frame lowering to always save and restore FP/LR, which adds unnecessary code.
This change does the same thing as SelectionDAG and ports over some code that scans
instructions after selection, using TargetInstrInfo to determine if target opcodes
are known calls.
Code size geomean improvements on CTMark:
-O0 : 0.1%
-Os : 0.3%
Differential Revision: https://reviews.llvm.org/D67868
Added:
llvm/trunk/test/CodeGen/AArch64/GlobalISel/tail-call-no-save-fp-lr.ll
Modified:
llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp
llvm/trunk/lib/CodeGen/GlobalISel/InstructionSelect.cpp
llvm/trunk/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
llvm/trunk/test/CodeGen/AArch64/GlobalISel/call-translator.ll
Modified: llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp?rev=372443&r1=372442&r2=372443&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp (original)
+++ llvm/trunk/lib/CodeGen/GlobalISel/IRTranslator.cpp Fri Sep 20 16:52:07 2019
@@ -1564,7 +1564,9 @@ bool IRTranslator::translateCallSite(con
Args.push_back(getOrCreateVRegs(*Arg));
}
- MF->getFrameInfo().setHasCalls(true);
+ // We don't set HasCalls on MFI here yet because call lowering may decide to
+ // optimize into tail calls. Instead, we defer that to selection where a final
+ // scan is done to check if any instructions are calls.
bool Success =
CLI->lowerCall(MIRBuilder, CS, Res, Args, SwiftErrorVReg,
[&]() { return getOrCreateVReg(*CS.getCalledValue()); });
Modified: llvm/trunk/lib/CodeGen/GlobalISel/InstructionSelect.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GlobalISel/InstructionSelect.cpp?rev=372443&r1=372442&r2=372443&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/GlobalISel/InstructionSelect.cpp (original)
+++ llvm/trunk/lib/CodeGen/GlobalISel/InstructionSelect.cpp Fri Sep 20 16:52:07 2019
@@ -17,7 +17,9 @@
#include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
@@ -223,6 +225,22 @@ bool InstructionSelect::runOnMachineFunc
auto &TLI = *MF.getSubtarget().getTargetLowering();
TLI.finalizeLowering(MF);
+ // Determine if there are any calls in this machine function. Ported from
+ // SelectionDAG.
+ MachineFrameInfo &MFI = MF.getFrameInfo();
+ for (const auto &MBB : MF) {
+ if (MFI.hasCalls() && MF.hasInlineAsm())
+ break;
+
+ for (const auto &MI : MBB) {
+ if ((MI.isCall() && !MI.isReturn()) || MI.isStackAligningInlineAsm())
+ MFI.setHasCalls(true);
+ if (MI.isInlineAsm())
+ MF.setHasInlineAsm(true);
+ }
+ }
+
+
LLVM_DEBUG({
dbgs() << "Rules covered by selecting function: " << MF.getName() << ":";
for (auto RuleID : CoverageInfo.covered())
Modified: llvm/trunk/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GlobalISel/LegalizerHelper.cpp?rev=372443&r1=372442&r2=372443&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/GlobalISel/LegalizerHelper.cpp (original)
+++ llvm/trunk/lib/CodeGen/GlobalISel/LegalizerHelper.cpp Fri Sep 20 16:52:07 2019
@@ -364,8 +364,6 @@ llvm::createLibcall(MachineIRBuilder &MI
auto &TLI = *MIRBuilder.getMF().getSubtarget().getTargetLowering();
const char *Name = TLI.getLibcallName(Libcall);
- MIRBuilder.getMF().getFrameInfo().setHasCalls(true);
-
CallLowering::CallLoweringInfo Info;
Info.CallConv = TLI.getLibcallCallingConv(Libcall);
Info.Callee = MachineOperand::CreateES(Name);
@@ -430,7 +428,6 @@ llvm::createMemLibcall(MachineIRBuilder
const char *Name = TLI.getLibcallName(RTLibcall);
MIRBuilder.setInstr(MI);
- MIRBuilder.getMF().getFrameInfo().setHasCalls(true);
CallLowering::CallLoweringInfo Info;
Info.CallConv = TLI.getLibcallCallingConv(RTLibcall);
Modified: llvm/trunk/test/CodeGen/AArch64/GlobalISel/call-translator.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/GlobalISel/call-translator.ll?rev=372443&r1=372442&r2=372443&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/GlobalISel/call-translator.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/GlobalISel/call-translator.ll Fri Sep 20 16:52:07 2019
@@ -100,7 +100,6 @@ define {double, i64, i32} @test_struct_r
}
; CHECK-LABEL: name: test_arr_call
-; CHECK: hasCalls: true
; CHECK: %0:_(p0) = COPY $x0
; CHECK: [[LD1:%[0-9]+]]:_(s64) = G_LOAD %0(p0) :: (load 8 from %ir.addr)
; CHECK: [[CST1:%[0-9]+]]:_(s64) = G_CONSTANT i64 8
Added: llvm/trunk/test/CodeGen/AArch64/GlobalISel/tail-call-no-save-fp-lr.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/GlobalISel/tail-call-no-save-fp-lr.ll?rev=372443&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/GlobalISel/tail-call-no-save-fp-lr.ll (added)
+++ llvm/trunk/test/CodeGen/AArch64/GlobalISel/tail-call-no-save-fp-lr.ll Fri Sep 20 16:52:07 2019
@@ -0,0 +1,20 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc %s -verify-machineinstrs -mtriple aarch64-apple-darwin -global-isel -global-isel-abort=1 -o - 2>&1 | FileCheck %s
+
+; Check that we get a tail call to foo without saving fp/lr.
+define void @bar(i32 %a) #1 {
+; CHECK-LABEL: bar:
+; CHECK: ; %bb.0: ; %entry
+; CHECK-NEXT: b _zoo
+entry:
+ tail call void @zoo(i32 undef)
+ ret void
+}
+
+define void @zoo(i32 %a) {
+entry:
+ ret void
+}
+
+attributes #1 = { "frame-pointer"="all" }
+
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