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AMDGPU/GlobalISel: Don't select boolean phi by default 

This is currently missing most of the hard parts to lower correctly,
so disable it for now. This fixes at least one OpenCL conformance test
and allows it to pass with fallback. Hide this behind an option for
now.
This commit is contained in:
Matt Arsenault 2020-05-19 23:03:39 -04:00
parent 222e0e58a8
commit 2dd7714b8d
3 changed files with 16 additions and 2 deletions
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14
llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
View File

@ -39,6 +39,12 @@
using namespace llvm;
using namespace MIPatternMatch;
static cl::opt<bool> AllowRiskySelect(
"amdgpu-global-isel-risky-select",
cl::desc("Allow GlobalISel to select cases that are likely to not work yet"),
cl::init(false),
cl::ReallyHidden);
#define GET_GLOBALISEL_IMPL
#define AMDGPUSubtarget GCNSubtarget
#include "AMDGPUGenGlobalISel.inc"
@ -196,6 +202,14 @@ bool AMDGPUInstructionSelector::selectCOPY(MachineInstr &I) const {
bool AMDGPUInstructionSelector::selectPHI(MachineInstr &I) const {
const Register DefReg = I.getOperand(0).getReg();
const LLT DefTy = MRI->getType(DefReg);
if (DefTy == LLT::scalar(1)) {
if (!AllowRiskySelect) {
LLVM_DEBUG(dbgs() << "Skipping risky boolean phi\n");
return false;
}
LLVM_DEBUG(dbgs() << "Selecting risky boolean phi\n");
}
// TODO: Verify this doesn't have insane operands (i.e. VGPR to SGPR copy)

2
llvm/test/CodeGen/AMDGPU/GlobalISel/divergent-control-flow.ll
View File

@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -global-isel -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -verify-machineinstrs < %s | FileCheck %s
; RUN: llc -global-isel -amdgpu-global-isel-risky-select -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -verify-machineinstrs < %s | FileCheck %s
; Make sure the branch targets are correct after lowering llvm.amdgcn.if

2
llvm/test/CodeGen/AMDGPU/GlobalISel/inst-select-phi.mir
View File

@ -1,5 +1,5 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
# RUN: llc -march=amdgcn -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s -check-prefix=GCN
# RUN: llc -march=amdgcn -amdgpu-global-isel-risky-select -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s -check-prefix=GCN
---
name: g_phi_s32_ss_sbranch