[GlobalISel] Add a fallback path to SDISel.

When global-isel fails on a MachineFunction MF, MF will be cleaned up
and given to SDISel.
Thanks to this fallback, we can already perform correctness test even if
we support only a small portion of the functions in a test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279891 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2016-08-27 00:18:31 +00:00
parent 1dba46c5a7
commit c47e5db5f7
6 changed files with 85 additions and 0 deletions

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@ -53,6 +53,8 @@ namespace llvm {
/// using the MIR serialization format.
MachineFunctionPass *createPrintMIRPass(raw_ostream &OS);
MachineFunctionPass *createResetMachineFunctionPass();
/// createCodeGenPreparePass - Transform the code to expose more pattern
/// matching during instruction selection.
FunctionPass *createCodeGenPreparePass(const TargetMachine *TM = nullptr);

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@ -292,6 +292,7 @@ void initializeRegionPrinterPass(PassRegistry&);
void initializeRegionViewerPass(PassRegistry&);
void initializeRegisterCoalescerPass(PassRegistry&);
void initializeRenameIndependentSubregsPass(PassRegistry&);
void initializeResetMachineFunctionPass(PassRegistry &);
void initializeReversePostOrderFunctionAttrsLegacyPassPass(PassRegistry&);
void initializeRewriteStatepointsForGCPass(PassRegistry&);
void initializeRewriteSymbolsLegacyPassPass(PassRegistry&);

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@ -105,6 +105,7 @@ add_llvm_library(LLVMCodeGen
RegisterUsageInfo.cpp
RegUsageInfoCollector.cpp
RegUsageInfoPropagate.cpp
ResetMachineFunctionPass.cpp
SafeStack.cpp
SafeStackColoring.cpp
SafeStackLayout.cpp

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@ -168,6 +168,15 @@ addPassesToGenerateCode(LLVMTargetMachine *TM, PassManagerBase &PM,
if (PassConfig->addGlobalInstructionSelect())
return nullptr;
// Pass to reset the MachineFunction if the ISel failed.
PM.add(createResetMachineFunctionPass());
// Provide a fallback path when we do not want to abort on
// not-yet-supported input.
if (LLVM_UNLIKELY(!PassConfig->isGlobalISelAbortEnabled()) &&
PassConfig->addInstSelector())
return nullptr;
} else if (PassConfig->addInstSelector())
return nullptr;

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@ -0,0 +1,53 @@
//===-- ResetMachineFunctionPass.cpp - Machine Loop Invariant Code Motion Pass ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
#define DEBUG_TYPE "reset-machine-function"
namespace {
class ResetMachineFunction : public MachineFunctionPass {
public:
static char ID; // Pass identification, replacement for typeid
ResetMachineFunction() :
MachineFunctionPass(ID) {
}
const char *getPassName() const override {
return "ResetMachineFunction";
}
bool runOnMachineFunction(MachineFunction &MF) override {
if (MF.getProperties().hasProperty(
MachineFunctionProperties::Property::FailedISel)) {
DEBUG(dbgs() << "Reseting: " << MF.getName() << '\n');
MF.reset();
return true;
}
return false;
}
};
} // end anonymous namespace
char ResetMachineFunction::ID = 0;
INITIALIZE_PASS(ResetMachineFunction, DEBUG_TYPE,
"reset machine function if ISel failed", false, false)
MachineFunctionPass *
llvm::createResetMachineFunctionPass() {
return new ResetMachineFunction();
}

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@ -0,0 +1,19 @@
; RUN: not llc -O0 -global-isel -verify-machineinstrs %s -o - 2>&1 | FileCheck %s --check-prefix=ERROR
; RUN: llc -O0 -global-isel -global-isel-abort=false -verify-machineinstrs %s -o - 2>&1 | FileCheck %s --check-prefix=FALLBACK
; This file checks that the fallback path to selection dag works.
; The test is fragile in the sense that it must be updated to expose
; something that fails with global-isel.
; When we cannot produce a test case anymore, that means we can remove
; the fallback path.
target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
target triple = "aarch64-apple-ios"
; ERROR: Unable to lower arguments
; FALLBACK: ldr q0,
; FALLBACK-NEXT: bl ___fixunstfti
define i128 @ABIi128(i128 %arg1) {
%farg1 = bitcast i128 %arg1 to fp128
%res = fptoui fp128 %farg1 to i128
ret i128 %res
}