[llvm] 52e5683 - [GlobalISel][ARM] Legalization of G_CONSTANT using constant pool (#98308)
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Mon Oct 14 02:40:24 PDT 2024
Author: Serge Pavlov
Date: 2024-10-14T16:40:21+07:00
New Revision: 52e5683ddddad787caf15c8edfd34eb4a9c8704a
URL: https://github.com/llvm/llvm-project/commit/52e5683ddddad787caf15c8edfd34eb4a9c8704a
DIFF: https://github.com/llvm/llvm-project/commit/52e5683ddddad787caf15c8edfd34eb4a9c8704a.diff
LOG: [GlobalISel][ARM] Legalization of G_CONSTANT using constant pool (#98308)
ARM uses complex encoding of immediate values using small number of
bits. As a result, some values cannot be represented as immediate
operands, they need to be synthesized in a register. This change
implements legalization of such constants with loading values from
constant pool.
---------
Co-authored-by: Matt Arsenault <arsenm2 at gmail.com>
Added:
llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-const.mir
llvm/test/CodeGen/ARM/GlobalISel/select-constpool.mir
Modified:
llvm/lib/Target/ARM/ARMInstructionSelector.cpp
llvm/lib/Target/ARM/ARMLegalizerInfo.cpp
llvm/lib/Target/ARM/ARMLegalizerInfo.h
llvm/lib/Target/ARM/ARMRegisterBankInfo.cpp
llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-fp.mir
Removed:
################################################################################
diff --git a/llvm/lib/Target/ARM/ARMInstructionSelector.cpp b/llvm/lib/Target/ARM/ARMInstructionSelector.cpp
index 3b3c380e1e1b32..ea18e6652c656f 100644
--- a/llvm/lib/Target/ARM/ARMInstructionSelector.cpp
+++ b/llvm/lib/Target/ARM/ARMInstructionSelector.cpp
@@ -14,6 +14,7 @@
#include "ARMSubtarget.h"
#include "ARMTargetMachine.h"
#include "llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h"
+#include "llvm/CodeGen/GlobalISel/GenericMachineInstrs.h"
#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
@@ -1088,7 +1089,7 @@ bool ARMInstructionSelector::select(MachineInstr &I) {
return selectGlobal(MIB, MRI);
case G_STORE:
case G_LOAD: {
- const auto &MemOp = **I.memoperands_begin();
+ auto &MemOp = **I.memoperands_begin();
if (MemOp.isAtomic()) {
LLVM_DEBUG(dbgs() << "Atomic load/store not supported yet\n");
return false;
@@ -1103,6 +1104,26 @@ bool ARMInstructionSelector::select(MachineInstr &I) {
assert((ValSize != 64 || STI.hasVFP2Base()) &&
"Don't know how to load/store 64-bit value without VFP");
+ if (auto *LoadMI = dyn_cast<GLoad>(&I)) {
+ Register PtrReg = LoadMI->getPointerReg();
+ MachineInstr *Ptr = MRI.getVRegDef(PtrReg);
+ if (Ptr->getOpcode() == TargetOpcode::G_CONSTANT_POOL) {
+ const MachineOperand &Index = Ptr->getOperand(1);
+ unsigned Opcode = Subtarget->isThumb() ? ARM::tLDRpci : ARM::LDRcp;
+
+ auto Instr = BuildMI(MBB, I, I.getDebugLoc(), TII.get(Opcode))
+ .addDef(Reg)
+ .add(Index)
+ .addImm(0)
+ .add(predOps(ARMCC::AL))
+ .addMemOperand(&MemOp);
+ if (!constrainSelectedInstRegOperands(*Instr, TII, TRI, RBI))
+ return false;
+ I.eraseFromParent();
+ return true;
+ }
+ }
+
const auto NewOpc = selectLoadStoreOpCode(I.getOpcode(), RegBank, ValSize);
if (NewOpc == G_LOAD || NewOpc == G_STORE)
return false;
diff --git a/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp b/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp
index 660f351bae64b7..452e908fdad98f 100644
--- a/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMLegalizerInfo.cpp
@@ -29,7 +29,7 @@ static bool AEABI(const ARMSubtarget &ST) {
return ST.isTargetAEABI() || ST.isTargetGNUAEABI() || ST.isTargetMuslAEABI();
}
-ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) {
+ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) : ST(ST) {
using namespace TargetOpcode;
const LLT p0 = LLT::pointer(0, 32);
@@ -99,9 +99,11 @@ ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) {
.minScalar(0, s32);
getActionDefinitionsBuilder(G_CONSTANT)
- .legalFor({s32, p0})
+ .customFor({s32, p0})
.clampScalar(0, s32, s32);
+ getActionDefinitionsBuilder(G_CONSTANT_POOL).legalFor({p0});
+
getActionDefinitionsBuilder(G_ICMP)
.legalForCartesianProduct({s1}, {s32, p0})
.minScalar(1, s32);
@@ -435,6 +437,13 @@ bool ARMLegalizerInfo::legalizeCustom(LegalizerHelper &Helper, MachineInstr &MI,
}
break;
}
+ case G_CONSTANT: {
+ const ConstantInt *ConstVal = MI.getOperand(1).getCImm();
+ uint64_t ImmVal = ConstVal->getZExtValue();
+ if (ConstantMaterializationCost(ImmVal, &ST) > 2 && !ST.genExecuteOnly())
+ return Helper.lowerConstant(MI) == LegalizerHelper::Legalized;
+ return true;
+ }
case G_FCONSTANT: {
// Convert to integer constants, while preserving the binary representation.
auto AsInteger =
diff --git a/llvm/lib/Target/ARM/ARMLegalizerInfo.h b/llvm/lib/Target/ARM/ARMLegalizerInfo.h
index 9e10638233e6d1..f7edf0b1612c53 100644
--- a/llvm/lib/Target/ARM/ARMLegalizerInfo.h
+++ b/llvm/lib/Target/ARM/ARMLegalizerInfo.h
@@ -59,6 +59,8 @@ class ARMLegalizerInfo : public LegalizerInfo {
// Get the libcall(s) corresponding to \p Predicate for operands of \p Size
// bits.
FCmpLibcallsList getFCmpLibcalls(CmpInst::Predicate, unsigned Size) const;
+
+ const ARMSubtarget &ST;
};
} // End llvm namespace.
#endif
diff --git a/llvm/lib/Target/ARM/ARMRegisterBankInfo.cpp b/llvm/lib/Target/ARM/ARMRegisterBankInfo.cpp
index 447db18b8defa1..0493fd9e317d5c 100644
--- a/llvm/lib/Target/ARM/ARMRegisterBankInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMRegisterBankInfo.cpp
@@ -329,6 +329,7 @@ ARMRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
case G_CONSTANT:
case G_FRAME_INDEX:
case G_GLOBAL_VALUE:
+ case G_CONSTANT_POOL:
OperandsMapping =
getOperandsMapping({&ARM::ValueMappings[ARM::GPR3OpsIdx], nullptr});
break;
diff --git a/llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-const.mir b/llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-const.mir
new file mode 100644
index 00000000000000..70d4a527493c3a
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-const.mir
@@ -0,0 +1,20 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple arm-- -run-pass=legalizer %s -o - | FileCheck %s
+
+---
+name: get_const
+legalized: false
+regBankSelected: false
+selected: false
+tracksRegLiveness: true
+body: |
+ bb.1.entry:
+ ; CHECK-LABEL: name: get_const
+ ; CHECK: [[CONSTANT_POOL:%[0-9]+]]:_(p0) = G_CONSTANT_POOL %const.0
+ ; CHECK-NEXT: [[LOAD:%[0-9]+]]:_(s32) = G_LOAD [[CONSTANT_POOL]](p0) :: (load (s32) from constant-pool)
+ ; CHECK-NEXT: $r0 = COPY [[LOAD]](s32)
+ ; CHECK-NEXT: MOVPCLR 14 /* CC::al */, $noreg, implicit $r0
+ %0:_(s32) = G_CONSTANT i32 287454020
+ $r0 = COPY %0(s32)
+ MOVPCLR 14 /* CC::al */, $noreg, implicit $r0
+...
diff --git a/llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-fp.mir b/llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-fp.mir
index 96461e044813d4..a35f82722adaf4 100644
--- a/llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-fp.mir
+++ b/llvm/test/CodeGen/ARM/GlobalISel/arm-legalize-fp.mir
@@ -1,9 +1,9 @@
# RUN: llc -O0 -mtriple arm-linux-gnueabihf -mattr=+vfp2 -float-abi=hard -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix HARD
-# RUN: llc -O0 -mtriple arm-linux-gnueabi -mattr=+vfp2,+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix SOFT-AEABI
-# RUN: llc -O0 -mtriple arm-linux-gnu -mattr=+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix SOFT-DEFAULT
+# RUN: llc -O0 -mtriple arm-linux-gnueabi -mattr=+vfp2,+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix SOFT-AEABI -check-prefix SOFT_POOL
+# RUN: llc -O0 -mtriple arm-linux-gnu -mattr=+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix SOFT-DEFAULT -check-prefix SOFT_POOL
# RUN: llc -O0 -mtriple thumb-linux-gnueabihf -mattr=+v6t2,+vfp2 -float-abi=hard -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix HARD
-# RUN: llc -O0 -mtriple thumb-linux-gnueabi -mattr=+v6t2,+vfp2,+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix SOFT-AEABI
-# RUN: llc -O0 -mtriple thumb-linux-gnu -mattr=+v6t2,+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix SOFT-DEFAULT
+# RUN: llc -O0 -mtriple thumb-linux-gnueabi -mattr=+v6t2,+vfp2,+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix=SOFT-AEABI -check-prefix SOFT_CONST
+# RUN: llc -O0 -mtriple thumb-linux-gnu -mattr=+v6t2,+soft-float -float-abi=soft -run-pass=legalizer %s -o - | FileCheck %s -check-prefix CHECK -check-prefix SOFT -check-prefix SOFT-DEFAULT -check-prefix SOFT_CONST
--- |
define void @test_frem_float() { ret void }
define void @test_frem_double() { ret void }
@@ -657,10 +657,20 @@ body: |
bb.0:
liveins:
+ ; SOFT_POOL: constants:
+ ; SOFT_POOL: id: 0
+ ; SOFT_POOL: value: i32 -1073532109
+ ; SOFT_POOL: id: 1
+ ; SOFT_POOL: value: i32 858993459
+
; HARD: [[R:%[0-9]+]]:_(s64) = G_FCONSTANT double -2.4
; SOFT-NOT: G_FCONSTANT
- ; SOFT-DAG: [[HI:%[0-9]+]]:_(s32) = G_CONSTANT i32 -1073532109
- ; SOFT-DAG: [[LO:%[0-9]+]]:_(s32) = G_CONSTANT i32 858993459
+ ; SOFT_CONST-DAG: [[HI:%[0-9]+]]:_(s32) = G_CONSTANT i32 -1073532109
+ ; SOFT_CONST-DAG: [[LO:%[0-9]+]]:_(s32) = G_CONSTANT i32 858993459
+ ; SOFT_POOL-DAG: [[HIPTR:%[0-9]+]]:_(p0) = G_CONSTANT_POOL %const.0
+ ; SOFT_POOL-DAG: [[HI:%[0-9]+]]:_(s32) = G_LOAD [[HIPTR]]
+ ; SOFT_POOL-DAG: [[LOPTR:%[0-9]+]]:_(p0) = G_CONSTANT_POOL %const.1
+ ; SOFT_POOL-DAG: [[LO:%[0-9]+]]:_(s32) = G_LOAD [[LOPTR]]
; SOFT-NOT: G_FCONSTANT
%0(s64) = G_FCONSTANT double -2.4
; HARD-DAG: G_UNMERGE_VALUES [[R]](s64)
diff --git a/llvm/test/CodeGen/ARM/GlobalISel/select-constpool.mir b/llvm/test/CodeGen/ARM/GlobalISel/select-constpool.mir
new file mode 100644
index 00000000000000..1c16c37e8b5cd5
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/GlobalISel/select-constpool.mir
@@ -0,0 +1,25 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple arm-- -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s
+
+---
+name: get_const
+legalized: true
+regBankSelected: true
+selected: false
+tracksRegLiveness: true
+constants:
+ - id: 0
+ value: i32 287454020
+ alignment: 4
+ isTargetSpecific: false
+body: |
+ bb.1.entry:
+ ; CHECK-LABEL: name: get_const
+ ; CHECK: [[LDRcp:%[0-9]+]]:gpr = LDRcp %const.0, 0, 14 /* CC::al */, $noreg :: (load (s32) from constant-pool)
+ ; CHECK-NEXT: $r0 = COPY [[LDRcp]]
+ ; CHECK-NEXT: MOVPCLR 14 /* CC::al */, $noreg, implicit $r0
+ %1:gprb(p0) = G_CONSTANT_POOL %const.0
+ %0:gprb(s32) = G_LOAD %1(p0) :: (load (s32) from constant-pool)
+ $r0 = COPY %0(s32)
+ MOVPCLR 14 /* CC::al */, $noreg, implicit $r0
+...
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