[llvm] 23f657c - [AArch64][GlobalISel] Emit bzero on Darwin
Jessica Paquette via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 25 17:14:47 PDT 2021
Author: Jessica Paquette
Date: 2021-03-25T17:14:25-07:00
New Revision: 23f657c165da1b599d79de11980583968d8e6a91
URL: https://github.com/llvm/llvm-project/commit/23f657c165da1b599d79de11980583968d8e6a91
DIFF: https://github.com/llvm/llvm-project/commit/23f657c165da1b599d79de11980583968d8e6a91.diff
LOG: [AArch64][GlobalISel] Emit bzero on Darwin
Darwin platforms for both AArch64 and X86 can provide optimized `bzero()`
routines. In this case, it may be preferable to use `bzero` in place of a
memset of 0.
This adds a G_BZERO generic opcode, similar to G_MEMSET et al. This opcode can
be generated by platforms which may want to use bzero.
To emit the G_BZERO, this adds a pre-legalize combine for AArch64. The
conditions for this are largely a port of the bzero case in
`AArch64SelectionDAGInfo::EmitTargetCodeForMemset`.
The only difference in comparison to the SelectionDAG code is that, when
compiling for minsize, this will fire for all memsets of 0. The original code
notes that it's not beneficial to do this for small memsets; however, using
bzero here will save a mov from wzr. For minsize, I think that it's preferable
to prioritise omitting the mov.
This also fixes a bug in the libcall legalization code which would delete
instructions which could not be legalized. It also adds a check to make sure
that we actually get a libcall name.
Code size improvements (Darwin):
- CTMark -Os: -0.0% geomean (-0.1% on pairlocalalign)
- CTMark -Oz: -0.2% geomean (-0.5% on bullet)
Differential Revision: https://reviews.llvm.org/D99358
Added:
llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero-unsupported.mir
llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero.mir
llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-bzero.mir
llvm/test/MachineVerifier/test_g_bzero.mir
Modified:
llvm/include/llvm/Support/TargetOpcodes.def
llvm/include/llvm/Target/GenericOpcodes.td
llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
llvm/lib/CodeGen/MachineVerifier.cpp
llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
llvm/lib/Target/AArch64/GISel/AArch64PreLegalizerCombiner.cpp
llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
Removed:
################################################################################
diff --git a/llvm/include/llvm/Support/TargetOpcodes.def b/llvm/include/llvm/Support/TargetOpcodes.def
index 3d450d5adc678..4228b67f52571 100644
--- a/llvm/include/llvm/Support/TargetOpcodes.def
+++ b/llvm/include/llvm/Support/TargetOpcodes.def
@@ -731,6 +731,7 @@ HANDLE_TARGET_OPCODE(G_MEMMOVE)
/// llvm.memset intrinsic
HANDLE_TARGET_OPCODE(G_MEMSET)
+HANDLE_TARGET_OPCODE(G_BZERO)
/// Vector reductions
HANDLE_TARGET_OPCODE(G_VECREDUCE_SEQ_FADD)
diff --git a/llvm/include/llvm/Target/GenericOpcodes.td b/llvm/include/llvm/Target/GenericOpcodes.td
index c8b72ee0df516..72c602d30694a 100644
--- a/llvm/include/llvm/Target/GenericOpcodes.td
+++ b/llvm/include/llvm/Target/GenericOpcodes.td
@@ -1354,6 +1354,13 @@ def G_MEMSET : GenericInstruction {
let mayStore = true;
}
+def G_BZERO : GenericInstruction {
+ let OutOperandList = (outs);
+ let InOperandList = (ins ptype0:$dst_addr, type1:$size, untyped_imm_0:$tailcall);
+ let hasSideEffects = false;
+ let mayStore = true;
+}
+
//------------------------------------------------------------------------------
// Bitfield extraction.
//------------------------------------------------------------------------------
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 9005f197ea4cd..21114daee2446 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -582,7 +582,11 @@ llvm::createMemLibcall(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
auto &CLI = *MIRBuilder.getMF().getSubtarget().getCallLowering();
auto &TLI = *MIRBuilder.getMF().getSubtarget().getTargetLowering();
RTLIB::Libcall RTLibcall;
- switch (MI.getOpcode()) {
+ unsigned Opc = MI.getOpcode();
+ switch (Opc) {
+ case TargetOpcode::G_BZERO:
+ RTLibcall = RTLIB::BZERO;
+ break;
case TargetOpcode::G_MEMCPY:
RTLibcall = RTLIB::MEMCPY;
break;
@@ -597,6 +601,13 @@ llvm::createMemLibcall(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
}
const char *Name = TLI.getLibcallName(RTLibcall);
+ // Unsupported libcall on the target.
+ if (!Name) {
+ LLVM_DEBUG(dbgs() << ".. .. Could not find libcall name for "
+ << MIRBuilder.getTII().getName(Opc) << "\n");
+ return LegalizerHelper::UnableToLegalize;
+ }
+
CallLowering::CallLoweringInfo Info;
Info.CallConv = TLI.getLibcallCallingConv(RTLibcall);
Info.Callee = MachineOperand::CreateES(Name);
@@ -748,10 +759,14 @@ LegalizerHelper::libcall(MachineInstr &MI) {
return Status;
break;
}
+ case TargetOpcode::G_BZERO:
case TargetOpcode::G_MEMCPY:
case TargetOpcode::G_MEMMOVE:
case TargetOpcode::G_MEMSET: {
- LegalizeResult Result = createMemLibcall(MIRBuilder, *MIRBuilder.getMRI(), MI);
+ LegalizeResult Result =
+ createMemLibcall(MIRBuilder, *MIRBuilder.getMRI(), MI);
+ if (Result != Legalized)
+ return Result;
MI.eraseFromParent();
return Result;
}
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index af8b84e8aaf21..9966600e1e628 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1509,26 +1509,28 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
break;
}
+ case TargetOpcode::G_BZERO:
case TargetOpcode::G_MEMSET: {
ArrayRef<MachineMemOperand *> MMOs = MI->memoperands();
+ std::string Name = Opc == TargetOpcode::G_MEMSET ? "memset" : "bzero";
if (MMOs.size() != 1) {
- report("memset must have 1 memory operand", MI);
+ report(Twine(Name, " must have 1 memory operand"), MI);
break;
}
if ((!MMOs[0]->isStore() || MMOs[0]->isLoad())) {
- report("memset memory operand must be a store", MI);
+ report(Twine(Name, " memory operand must be a store"), MI);
break;
}
LLT DstPtrTy = MRI->getType(MI->getOperand(0).getReg());
if (!DstPtrTy.isPointer()) {
- report("memset operand must be a pointer", MI);
+ report(Twine(Name, " operand must be a pointer"), MI);
break;
}
if (DstPtrTy.getAddressSpace() != MMOs[0]->getAddrSpace())
- report("inconsistent memset address space", MI);
+ report("inconsistent " + Twine(Name, " address space"), MI);
break;
}
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
index 0190ca3c883c6..b5ea4eb462364 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -682,7 +682,8 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
getActionDefinitionsBuilder(G_DYN_STACKALLOC).lower();
- getActionDefinitionsBuilder({G_MEMCPY, G_MEMMOVE, G_MEMSET}).libcall();
+ getActionDefinitionsBuilder({G_BZERO, G_MEMCPY, G_MEMMOVE, G_MEMSET})
+ .libcall();
getActionDefinitionsBuilder(G_ABS).lowerIf(
[=](const LegalityQuery &Query) { return Query.Types[0].isScalar(); });
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64PreLegalizerCombiner.cpp b/llvm/lib/Target/AArch64/GISel/AArch64PreLegalizerCombiner.cpp
index 26029b4db11f5..4efc63ea68b74 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64PreLegalizerCombiner.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64PreLegalizerCombiner.cpp
@@ -217,6 +217,46 @@ static bool applyFoldGlobalOffset(MachineInstr &MI, MachineRegisterInfo &MRI,
return true;
}
+/// Replace a G_MEMSET with a value of 0 with a G_BZERO instruction if it is
+/// supported and beneficial to do so.
+///
+/// \note This only applies on Darwin.
+///
+/// \returns true if \p MI was replaced with a G_BZERO.
+static bool tryEmitBZero(MachineInstr &MI, MachineIRBuilder &MIRBuilder,
+ bool MinSize) {
+ assert(MI.getOpcode() == TargetOpcode::G_MEMSET);
+ MachineRegisterInfo &MRI = *MIRBuilder.getMRI();
+ auto &TLI = *MIRBuilder.getMF().getSubtarget().getTargetLowering();
+ if (!TLI.getLibcallName(RTLIB::BZERO))
+ return false;
+ auto Zero = getConstantVRegValWithLookThrough(MI.getOperand(1).getReg(), MRI);
+ if (!Zero || Zero->Value.getSExtValue() != 0)
+ return false;
+
+ // It's not faster to use bzero rather than memset for sizes <= 256.
+ // However, it *does* save us a mov from wzr, so if we're going for
+ // minsize, use bzero even if it's slower.
+ if (!MinSize) {
+ // If the size is known, check it. If it is not known, assume using bzero is
+ // better.
+ if (auto Size =
+ getConstantVRegValWithLookThrough(MI.getOperand(2).getReg(), MRI)) {
+ if (Size->Value.getSExtValue() <= 256)
+ return false;
+ }
+ }
+
+ MIRBuilder.setInstrAndDebugLoc(MI);
+ MIRBuilder
+ .buildInstr(TargetOpcode::G_BZERO, {},
+ {MI.getOperand(0), MI.getOperand(2)})
+ .addImm(MI.getOperand(3).getImm())
+ .addMemOperand(*MI.memoperands_begin());
+ MI.eraseFromParent();
+ return true;
+}
+
class AArch64PreLegalizerCombinerHelperState {
protected:
CombinerHelper &Helper;
@@ -263,7 +303,8 @@ bool AArch64PreLegalizerCombinerInfo::combine(GISelChangeObserver &Observer,
if (Generated.tryCombineAll(Observer, MI, B))
return true;
- switch (MI.getOpcode()) {
+ unsigned Opc = MI.getOpcode();
+ switch (Opc) {
case TargetOpcode::G_CONCAT_VECTORS:
return Helper.tryCombineConcatVectors(MI);
case TargetOpcode::G_SHUFFLE_VECTOR:
@@ -275,7 +316,11 @@ bool AArch64PreLegalizerCombinerInfo::combine(GISelChangeObserver &Observer,
// heuristics decide.
unsigned MaxLen = EnableOpt ? 0 : 32;
// Try to inline memcpy type calls if optimizations are enabled.
- return !EnableMinSize ? Helper.tryCombineMemCpyFamily(MI, MaxLen) : false;
+ if (!EnableMinSize && Helper.tryCombineMemCpyFamily(MI, MaxLen))
+ return true;
+ if (Opc == TargetOpcode::G_MEMSET)
+ return tryEmitBZero(MI, B, EnableMinSize);
+ return false;
}
}
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero-unsupported.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero-unsupported.mir
new file mode 100644
index 0000000000000..f12a125b2f73b
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero-unsupported.mir
@@ -0,0 +1,14 @@
+# RUN: not llc -mtriple=aarch64 -global-isel-abort=1 -run-pass=legalizer -verify-machineinstrs %s -o /dev/null 2>&1 | FileCheck %s
+# RUN: not llc -mtriple=aarch64-linux-gnu -global-isel-abort=1 -run-pass=legalizer -verify-machineinstrs %s -o /dev/null 2>&1 | FileCheck %s
+...
+---
+name: bzero
+tracksRegLiveness: true
+body: |
+ bb.0:
+ # CHECK: LLVM ERROR: unable to legalize instruction: G_BZERO
+ liveins: $x0, $x1
+ %ptr:_(p0) = COPY $x0
+ %width:_(s64) = COPY $x1
+ G_BZERO %ptr(p0), %width(s64), 0 :: (store 4)
+ RET_ReallyLR
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero.mir
new file mode 100644
index 0000000000000..9e4908396d9d2
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalize-bzero.mir
@@ -0,0 +1,45 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=aarch64-apple-ios -run-pass=legalizer -verify-machineinstrs %s -o - | FileCheck %s
+
+# Check that we can legalize G_BZERO on Darwin.
+
+...
+---
+name: bzero
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x0, $x1
+ ; CHECK-LABEL: name: bzero
+ ; CHECK: liveins: $x0, $x1
+ ; CHECK: %ptr:_(p0) = COPY $x0
+ ; CHECK: %width:_(s64) = COPY $x1
+ ; CHECK: ADJCALLSTACKDOWN 0, 0, implicit-def $sp, implicit $sp
+ ; CHECK: $x0 = COPY %ptr(p0)
+ ; CHECK: $x1 = COPY %width(s64)
+ ; CHECK: BL &bzero, csr_darwin_aarch64_aapcs, implicit-def $lr, implicit $sp, implicit $x0, implicit $x1
+ ; CHECK: ADJCALLSTACKUP 0, 0, implicit-def $sp, implicit $sp
+ ; CHECK: RET_ReallyLR
+ %ptr:_(p0) = COPY $x0
+ %width:_(s64) = COPY $x1
+ G_BZERO %ptr(p0), %width(s64), 0 :: (store 4)
+ RET_ReallyLR
+
+...
+---
+name: bzero_tail_call
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x0, $x1
+ ; CHECK-LABEL: name: bzero_tail_call
+ ; CHECK: liveins: $x0, $x1
+ ; CHECK: %ptr:_(p0) = COPY $x0
+ ; CHECK: %width:_(s64) = COPY $x1
+ ; CHECK: $x0 = COPY %ptr(p0)
+ ; CHECK: $x1 = COPY %width(s64)
+ ; CHECK: TCRETURNdi &bzero, 0, csr_darwin_aarch64_aapcs, implicit $sp, implicit $x0, implicit $x1
+ %ptr:_(p0) = COPY $x0
+ %width:_(s64) = COPY $x1
+ G_BZERO %ptr(p0), %width(s64), 1 :: (store 4)
+ RET_ReallyLR
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
index a153339f6b6b0..eb4efb95fa718 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
@@ -619,6 +619,7 @@
# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: G_MEMCPY (opcode {{[0-9]+}}): 3 type indices, 1 imm index
+# DEBUG-NEXT: .. opcode {{[0-9]+}} is aliased to {{[0-9]+}}
# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: G_MEMMOVE (opcode {{[0-9]+}}): 3 type indices, 1 imm index
@@ -629,6 +630,9 @@
# DEBUG-NEXT: .. opcode {{[0-9]+}} is aliased to {{[0-9]+}}
# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: G_BZERO (opcode {{[0-9]+}}): 2 type indices, 1 imm index
+# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: G_VECREDUCE_SEQ_FADD (opcode {{[0-9]+}}): 3 type indices, 0 imm indices
# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-bzero.mir b/llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-bzero.mir
new file mode 100644
index 0000000000000..73fd9d17230ca
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-bzero.mir
@@ -0,0 +1,147 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple aarch64-apple-ios -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs %s -o - | FileCheck %s --check-prefix=DARWIN
+# RUN: llc -mtriple aarch64 -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs %s -o - | FileCheck %s --check-prefix=UNKNOWN
+#
+# Check that on Darwin we can combine to G_BZERO. Without Darwin, this should
+# stay as memset.
+
+--- |
+ define void @bzero_unknown_width() { unreachable }
+ define void @bzero_tail_unknown_width() { unreachable }
+ define void @bzero_constant_width() { unreachable }
+ define void @bzero_constant_width_minsize() minsize { unreachable }
+ define void @not_zero() minsize { unreachable }
+...
+---
+name: bzero_unknown_width
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x0, $x1
+ ; Always use G_BZERO when the memset width is unknown on Darwin.
+
+ ; DARWIN-LABEL: name: bzero_unknown_width
+ ; DARWIN: liveins: $x0, $x1
+ ; DARWIN: %ptr:_(p0) = COPY $x0
+ ; DARWIN: %width:_(s64) = COPY $x1
+ ; DARWIN: G_BZERO %ptr(p0), %width(s64), 0 :: (store 4)
+ ; DARWIN: RET_ReallyLR
+ ; UNKNOWN-LABEL: name: bzero_unknown_width
+ ; UNKNOWN: liveins: $x0, $x1
+ ; UNKNOWN: %ptr:_(p0) = COPY $x0
+ ; UNKNOWN: %zero:_(s8) = G_CONSTANT i8 0
+ ; UNKNOWN: %width:_(s64) = COPY $x1
+ ; UNKNOWN: G_MEMSET %ptr(p0), %zero(s8), %width(s64), 0 :: (store 4)
+ ; UNKNOWN: RET_ReallyLR
+ %ptr:_(p0) = COPY $x0
+ %zero:_(s8) = G_CONSTANT i8 0
+ %width:_(s64) = COPY $x1
+ G_MEMSET %ptr(p0), %zero(s8), %width(s64), 0 :: (store 4)
+ RET_ReallyLR
+...
+---
+name: bzero_tail_unknown_width
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x0, $x1
+ ; DARWIN-LABEL: name: bzero_tail_unknown_width
+ ; DARWIN: liveins: $x0, $x1
+ ; DARWIN: %ptr:_(p0) = COPY $x0
+ ; DARWIN: %width:_(s64) = COPY $x1
+ ; DARWIN: G_BZERO %ptr(p0), %width(s64), 1 :: (store 4)
+ ; DARWIN: RET_ReallyLR
+ ; UNKNOWN-LABEL: name: bzero_tail_unknown_width
+ ; UNKNOWN: liveins: $x0, $x1
+ ; UNKNOWN: %ptr:_(p0) = COPY $x0
+ ; UNKNOWN: %zero:_(s8) = G_CONSTANT i8 0
+ ; UNKNOWN: %width:_(s64) = COPY $x1
+ ; UNKNOWN: G_MEMSET %ptr(p0), %zero(s8), %width(s64), 1 :: (store 4)
+ ; UNKNOWN: RET_ReallyLR
+ %ptr:_(p0) = COPY $x0
+ %zero:_(s8) = G_CONSTANT i8 0
+ %width:_(s64) = COPY $x1
+ G_MEMSET %ptr(p0), %zero(s8), %width(s64), 1 :: (store 4)
+ RET_ReallyLR
+...
+---
+name: bzero_constant_width
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x0, $x1
+ ; For values >256, we should use G_BZERO on Darwin.
+
+ ; DARWIN-LABEL: name: bzero_constant_width
+ ; DARWIN: liveins: $x0, $x1
+ ; DARWIN: %ptr:_(p0) = COPY $x0
+ ; DARWIN: %width:_(s64) = G_CONSTANT i64 1024
+ ; DARWIN: G_BZERO %ptr(p0), %width(s64), 0 :: (store 4)
+ ; DARWIN: RET_ReallyLR
+ ; UNKNOWN-LABEL: name: bzero_constant_width
+ ; UNKNOWN: liveins: $x0, $x1
+ ; UNKNOWN: %ptr:_(p0) = COPY $x0
+ ; UNKNOWN: %zero:_(s8) = G_CONSTANT i8 0
+ ; UNKNOWN: %width:_(s64) = G_CONSTANT i64 1024
+ ; UNKNOWN: G_MEMSET %ptr(p0), %zero(s8), %width(s64), 0 :: (store 4)
+ ; UNKNOWN: RET_ReallyLR
+ %ptr:_(p0) = COPY $x0
+ %zero:_(s8) = G_CONSTANT i8 0
+ %width:_(s64) = G_CONSTANT i64 1024
+ G_MEMSET %ptr(p0), %zero(s8), %width(s64), 0 :: (store 4)
+ RET_ReallyLR
+...
+---
+name: bzero_constant_width_minsize
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x0, $x1
+ ; With minsize, we should always use G_BZERO to avoid a copy from wzr.
+
+ ; DARWIN-LABEL: name: bzero_constant_width_minsize
+ ; DARWIN: liveins: $x0, $x1
+ ; DARWIN: %ptr:_(p0) = COPY $x0
+ ; DARWIN: %width:_(s64) = G_CONSTANT i64 256
+ ; DARWIN: G_BZERO %ptr(p0), %width(s64), 0 :: (store 4)
+ ; DARWIN: RET_ReallyLR
+ ; UNKNOWN-LABEL: name: bzero_constant_width_minsize
+ ; UNKNOWN: liveins: $x0, $x1
+ ; UNKNOWN: %ptr:_(p0) = COPY $x0
+ ; UNKNOWN: %zero:_(s8) = G_CONSTANT i8 0
+ ; UNKNOWN: %width:_(s64) = G_CONSTANT i64 256
+ ; UNKNOWN: G_MEMSET %ptr(p0), %zero(s8), %width(s64), 0 :: (store 4)
+ ; UNKNOWN: RET_ReallyLR
+ %ptr:_(p0) = COPY $x0
+ %zero:_(s8) = G_CONSTANT i8 0
+ %width:_(s64) = G_CONSTANT i64 256
+ G_MEMSET %ptr(p0), %zero(s8), %width(s64), 0 :: (store 4)
+ RET_ReallyLR
+...
+---
+name: not_zero
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $x0, $x1
+ ; When the value isn't 0, don't create G_BZERO.
+
+ ; DARWIN-LABEL: name: not_zero
+ ; DARWIN: liveins: $x0, $x1
+ ; DARWIN: %ptr:_(p0) = COPY $x0
+ ; DARWIN: %not_zero:_(s8) = G_CONSTANT i8 1
+ ; DARWIN: %width:_(s64) = G_CONSTANT i64 256
+ ; DARWIN: G_MEMSET %ptr(p0), %not_zero(s8), %width(s64), 0 :: (store 4)
+ ; DARWIN: RET_ReallyLR
+ ; UNKNOWN-LABEL: name: not_zero
+ ; UNKNOWN: liveins: $x0, $x1
+ ; UNKNOWN: %ptr:_(p0) = COPY $x0
+ ; UNKNOWN: %not_zero:_(s8) = G_CONSTANT i8 1
+ ; UNKNOWN: %width:_(s64) = G_CONSTANT i64 256
+ ; UNKNOWN: G_MEMSET %ptr(p0), %not_zero(s8), %width(s64), 0 :: (store 4)
+ ; UNKNOWN: RET_ReallyLR
+ %ptr:_(p0) = COPY $x0
+ %not_zero:_(s8) = G_CONSTANT i8 1
+ %width:_(s64) = G_CONSTANT i64 256
+ G_MEMSET %ptr(p0), %not_zero(s8), %width(s64), 0 :: (store 4)
+ RET_ReallyLR
diff --git a/llvm/test/MachineVerifier/test_g_bzero.mir b/llvm/test/MachineVerifier/test_g_bzero.mir
new file mode 100644
index 0000000000000..6e0212115aa6a
--- /dev/null
+++ b/llvm/test/MachineVerifier/test_g_bzero.mir
@@ -0,0 +1,33 @@
+#RUN: not --crash llc -o - -march=arm64 -run-pass=none -verify-machineinstrs %s 2>&1 | FileCheck %s
+# REQUIRES: aarch64-registered-target
+---
+name: test_bzero
+legalized: true
+regBankSelected: false
+selected: false
+tracksRegLiveness: true
+liveins:
+body: |
+ bb.0:
+
+ %ptr:_(p0) = G_IMPLICIT_DEF
+ %cst1:_(s64) = G_CONSTANT i64 4
+ %cst2:_(s8) = G_CONSTANT i8 7
+
+ ; CHECK: *** Bad machine code: bzero must have 1 memory operand ***
+ G_BZERO %ptr, %cst2, 0
+
+ ; CHECK: *** Bad machine code: bzero memory operand must be a store ***
+ G_BZERO %ptr, %cst2, 0 :: (load 4)
+
+ ; CHECK: *** Bad machine code: Missing mayLoad flag ***
+ ; CHECK: *** Bad machine code: bzero memory operand must be a store ***
+ G_BZERO %ptr, %cst2, 0 :: (load store 4)
+
+ ; CHECK: *** Bad machine code: inconsistent bzero address space ***
+ G_BZERO %ptr, %cst2, 0 :: (store 4, addrspace 1)
+
+ ; CHECK: *** Bad machine code: bzero operand must be a pointer ***
+ G_BZERO %cst1, %cst2, 0 :: (store 4)
+
+...
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