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[PowerPC] Fix i128 vcmpequb optimization for loads with range metadata and small constants #196801

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amy-kwan merged 4 commits into from
May 17, 2026
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[PowerPC] Fix i128 vcmpequb optimization for loads with range metadata and small constants #196801

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3ea0779
[PowerPC] Fix i128 vcmpequb optimization for loads with range metadat…
amy-kwan May 9, 2026
5071ab3
Apply clang-format.
amy-kwan May 10, 2026
dd1fd94
Address review comments for 32-bit
amy-kwan May 14, 2026
095f753
Update check prefix
amy-kwan May 14, 2026
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27 changes: 21 additions & 6 deletions llvm/lib/Target/PowerPC/PPCISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15797,8 +15797,14 @@ static bool canConvertToVcmpequb(SDValue &LHS, SDValue &RHS) {
if (Operand.getValueType() != MVT::i128)
return false;

if (Operand.getOpcode() == ISD::Constant)
return true;
if (Operand.getOpcode() == ISD::Constant) {
auto *C = cast<ConstantSDNode>(Operand);
const APInt &Val = C->getAPIntValue();
if (Val.ult(1ULL << 16))

@diggerlin diggerlin May 11, 2026

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I suggest that add a comment here " When comparing an i128 value loaded from memory against a constant, the comparison can be lowered to xori or or if the constant is less than 2¹⁶, since xori's immediate field is 16 bits wide."

and I guess comparing with constant zero when target is 32bit. convertTwoLoadsAndCmpToVCMPEQUB will has less instructions.

if (Val.ult(1ULL << 16))

-->

if (Val.ult(1ULL << 16) && DAG.getTargetLoweringInfo().getPointerTy(DAG.getDataLayout()).getSizeInBits() == 64 )

return false;
else
return true;
}

auto *LoadNode = dyn_cast<LoadSDNode>(Operand);
if (!LoadNode)
Expand Down Expand Up @@ -15849,10 +15855,19 @@ SDValue convertTwoLoadsAndCmpToVCMPEQUB(SelectionDAG &DAG, SDNode *N,
assert(Operand.getOpcode() == ISD::LOAD && "Must be LoadSDNode here.");

auto *LoadNode = cast<LoadSDNode>(Operand);
SDValue NewLoad =
DAG.getLoad(MVT::v16i8, DL, LoadNode->getChain(),
LoadNode->getBasePtr(), LoadNode->getMemOperand());
DAG.ReplaceAllUsesOfValueWith(Operand.getValue(1), NewLoad.getValue(1));
// Create a new MachineMemOperand without range metadata.
// Range metadata is only valid for integer scalar types, not vectors.
// The original i128 load may have range metadata, but when we convert
// to v16i8, that metadata is no longer semantically valid.
MachineMemOperand *MMO = LoadNode->getMemOperand();
MachineFunction &MF = DAG.getMachineFunction();
MachineMemOperand *NewMMO = MF.getMachineMemOperand(
MMO->getPointerInfo(), MMO->getFlags(), MMO->getSize(), MMO->getAlign(),
MMO->getAAInfo(), nullptr, MMO->getSyncScopeID(),
MMO->getSuccessOrdering(), MMO->getFailureOrdering());
SDValue NewLoad = DAG.getLoad(MVT::v16i8, DL, LoadNode->getChain(),
LoadNode->getBasePtr(), NewMMO);
DAG.ReplaceAllUsesOfValueWith(SDValue(LoadNode, 1), NewLoad.getValue(1));
return NewLoad;
};

Expand Down
210 changes: 210 additions & 0 deletions llvm/test/CodeGen/PowerPC/ppc-i128-cmp.ll
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@@ -0,0 +1,210 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
; RUN: llc -mcpu=pwr8 -ppc-asm-full-reg-names -mtriple=powerpc64-ibm-aix < %s | \
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amy-kwan marked this conversation as resolved.
; RUN: FileCheck %s --check-prefix=CHECK-AIX

@diggerlin diggerlin May 14, 2026

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change CHECK-AIX --> CHECK-AIX64

; RUN: llc -mcpu=pwr8 -ppc-asm-full-reg-names -mtriple=powerpc64le-unknown-linux-gnu < %s | \
; RUN: FileCheck %s --check-prefix=CHECK-LINUX

define i1 @test1() {
; CHECK-AIX-LABEL: test1:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: ld r3, 0(0)
; CHECK-AIX-NEXT: ld r4, 8(0)
; CHECK-AIX-NEXT: or r3, r4, r3
; CHECK-AIX-NEXT: cntlzd r3, r3
; CHECK-AIX-NEXT: rldicl r3, r3, 58, 63
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test1:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: ld r3, 8(0)
; CHECK-LINUX-NEXT: ld r4, 0(0)
; CHECK-LINUX-NEXT: or r3, r4, r3
; CHECK-LINUX-NEXT: cntlzd r3, r3
; CHECK-LINUX-NEXT: rldicl r3, r3, 58, 63
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16
%icmp = icmp eq i128 %load, 0
ret i1 %icmp
}

define i1 @test2() {
; CHECK-AIX-LABEL: test2:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: ld r4, 8(0)
; CHECK-AIX-NEXT: ld r3, 0(0)
; CHECK-AIX-NEXT: xori r4, r4, 10
; CHECK-AIX-NEXT: or r3, r4, r3
; CHECK-AIX-NEXT: cntlzd r3, r3
; CHECK-AIX-NEXT: rldicl r3, r3, 58, 63
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test2:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: ld r4, 0(0)
; CHECK-LINUX-NEXT: ld r3, 8(0)
; CHECK-LINUX-NEXT: xori r4, r4, 10
; CHECK-LINUX-NEXT: or r3, r4, r3
; CHECK-LINUX-NEXT: cntlzd r3, r3
; CHECK-LINUX-NEXT: rldicl r3, r3, 58, 63
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16
%icmp = icmp eq i128 %load, 10
ret i1 %icmp
}

define i1 @test3() {
; CHECK-AIX-LABEL: test3:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: ld r4, 8(0)
; CHECK-AIX-NEXT: ld r3, 0(0)
; CHECK-AIX-NEXT: xori r4, r4, 65535
; CHECK-AIX-NEXT: or r3, r4, r3
; CHECK-AIX-NEXT: cntlzd r3, r3
; CHECK-AIX-NEXT: rldicl r3, r3, 58, 63
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test3:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: ld r4, 0(0)
; CHECK-LINUX-NEXT: ld r3, 8(0)
; CHECK-LINUX-NEXT: xori r4, r4, 65535
; CHECK-LINUX-NEXT: or r3, r4, r3
; CHECK-LINUX-NEXT: cntlzd r3, r3
; CHECK-LINUX-NEXT: rldicl r3, r3, 58, 63
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16
%icmp = icmp eq i128 %load, 65535
ret i1 %icmp
}

define i1 @test4() {
; CHECK-AIX-LABEL: test4:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: li r3, 0
; CHECK-AIX-NEXT: lxvw4x vs34, 0, r3
; CHECK-AIX-NEXT: ld r3, L..C0(r2) # %const.0
; CHECK-AIX-NEXT: lxvd2x vs35, 0, r3
; CHECK-AIX-NEXT: vcmpequb. v2, v2, v3
; CHECK-AIX-NEXT: mfocrf r3, 2
; CHECK-AIX-NEXT: rlwinm r3, r3, 25, 31, 31
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test4:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: li r3, 0
; CHECK-LINUX-NEXT: lxvd2x vs34, 0, r3
; CHECK-LINUX-NEXT: addis r3, r2, .LCPI3_0@toc@ha
; CHECK-LINUX-NEXT: addi r3, r3, .LCPI3_0@toc@l
; CHECK-LINUX-NEXT: lxvd2x vs35, 0, r3
; CHECK-LINUX-NEXT: vcmpequb. v2, v2, v3
; CHECK-LINUX-NEXT: mfocrf r3, 2
; CHECK-LINUX-NEXT: rlwinm r3, r3, 25, 31, 31
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16
%icmp = icmp eq i128 %load, 65536
ret i1 %icmp
}

; Test using the !range metadata
define i1 @test5() {
; CHECK-AIX-LABEL: test5:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: ld r3, 0(0)
; CHECK-AIX-NEXT: ld r4, 8(0)
; CHECK-AIX-NEXT: or r3, r4, r3
; CHECK-AIX-NEXT: cntlzd r3, r3
; CHECK-AIX-NEXT: rldicl r3, r3, 58, 63
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test5:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: ld r3, 8(0)
; CHECK-LINUX-NEXT: ld r4, 0(0)
; CHECK-LINUX-NEXT: or r3, r4, r3
; CHECK-LINUX-NEXT: cntlzd r3, r3
; CHECK-LINUX-NEXT: rldicl r3, r3, 58, 63
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16, !range !0
%icmp = icmp eq i128 %load, 0
ret i1 %icmp
}

define i1 @test6() {
; CHECK-AIX-LABEL: test6:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: ld r4, 8(0)
; CHECK-AIX-NEXT: ld r3, 0(0)
; CHECK-AIX-NEXT: xori r4, r4, 65535
; CHECK-AIX-NEXT: or r3, r4, r3
; CHECK-AIX-NEXT: cntlzd r3, r3
; CHECK-AIX-NEXT: rldicl r3, r3, 58, 63
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test6:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: ld r4, 0(0)
; CHECK-LINUX-NEXT: ld r3, 8(0)
; CHECK-LINUX-NEXT: xori r4, r4, 65535
; CHECK-LINUX-NEXT: or r3, r4, r3
; CHECK-LINUX-NEXT: cntlzd r3, r3
; CHECK-LINUX-NEXT: rldicl r3, r3, 58, 63
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16, !range !1
%icmp = icmp eq i128 %load, 65535
ret i1 %icmp
}

define i1 @test7() {
; CHECK-AIX-LABEL: test7:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: li r3, 0
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test7:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: li r3, 0
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16, !range !1
%icmp = icmp eq i128 %load, 65536
ret i1 %icmp
}

define i1 @test8() {
; CHECK-AIX-LABEL: test8:
; CHECK-AIX: # %bb.0: # %bb
; CHECK-AIX-NEXT: li r3, 0
; CHECK-AIX-NEXT: lxvw4x vs34, 0, r3
; CHECK-AIX-NEXT: ld r3, L..C1(r2) # %const.0
; CHECK-AIX-NEXT: lxvd2x vs35, 0, r3
; CHECK-AIX-NEXT: vcmpequb. v2, v2, v3
; CHECK-AIX-NEXT: mfocrf r3, 2
; CHECK-AIX-NEXT: rlwinm r3, r3, 25, 31, 31
; CHECK-AIX-NEXT: blr
;
; CHECK-LINUX-LABEL: test8:
; CHECK-LINUX: # %bb.0: # %bb
; CHECK-LINUX-NEXT: li r3, 0
; CHECK-LINUX-NEXT: lxvd2x vs34, 0, r3
; CHECK-LINUX-NEXT: addis r3, r2, .LCPI7_0@toc@ha
; CHECK-LINUX-NEXT: addi r3, r3, .LCPI7_0@toc@l
; CHECK-LINUX-NEXT: lxvd2x vs35, 0, r3
; CHECK-LINUX-NEXT: vcmpequb. v2, v2, v3
; CHECK-LINUX-NEXT: mfocrf r3, 2
; CHECK-LINUX-NEXT: rlwinm r3, r3, 25, 31, 31
; CHECK-LINUX-NEXT: blr
bb:
%load = load i128, ptr null, align 16, !range !2
%icmp = icmp eq i128 %load, 65536
ret i1 %icmp
}

!0 = !{i128 0, i128 2}
!1 = !{i128 0, i128 65536}
!2 = !{i128 0, i128 65537}