Skip to content

[DAG] Rewrite demorgan rule for ANDN #163789

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
kper wants to merge 20 commits into from
Closed

[DAG] Rewrite demorgan rule for ANDN #163789

Show file tree
Hide file tree
Changes from 6 commits
Commits
Show all changes
20 commits
Select commit Hold shift + click to select a range
ee35653
[X86]: Reassoc demorgan rule for ANDN
kper Oct 16, 2025
deda338
[X86]: Removed obsolete code
kper Oct 16, 2025
cdb57ef
[DAG]: Reassoc demorgan rule for ANDN
kper Oct 16, 2025
9e4103d
[DAG]: Fixed type
kper Oct 16, 2025
cf6ee58
[X86]: Updated tests
kper Oct 16, 2025
cef0067
[DAG]: Updated tests
kper Oct 16, 2025
e31e5ab
[DAG]: Updated tests
kper Oct 17, 2025
cf9da83
Revert "[DAG]: Updated tests"
kper Oct 18, 2025
3a90a69
Revert "[DAG]: Updated tests"
kper Oct 18, 2025
1245b6b
[DAG]: Rewrite `~(a | b | c)` into `~a & ~b & ~c`
kper Oct 18, 2025
746b101
[X86]: Created new test
kper Oct 18, 2025
f237020
[DAG]: Run fmt
kper Oct 18, 2025
956b849
[AArch64]: Updated tests
kper Oct 18, 2025
643e4d5
[X86]: Updated tests
kper Oct 18, 2025
e2032ef
[PowerPC]: Updated tests
kper Oct 18, 2025
5218588
[X86]: Removed reversing of rewriting demorgan
kper Oct 18, 2025
de10f4a
[X86][PowerPC][AArch64]: Updated tests
kper Oct 18, 2025
c95c10a
[LoongArch][SystemZ]: Updated tests
kper Oct 22, 2025
3681932
[AArch64][PowerPC]: Reverting some updates
kper Oct 22, 2025
b3ec648
[X86]: Removed comment
kper Oct 22, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
17 changes: 17 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10197,6 +10197,23 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
}
}

// fold (not (or A, B)) -> and(not(A), not(B))
if (TLI.hasAndNot(SDValue(N, 0))) {
// If we have AndNot then it is profitable to apply demorgan to make use
// of the machine instruction.
Comment on lines +10202 to +10203
Copy link
Contributor

@jayfoad jayfoad Oct 17, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I would argue that this fold is not profitable at all on its own. It is only profitable when combined into a larger pattern like ~(A|B|C).

Copy link
Contributor Author

@kper kper Oct 17, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yeah that's also my impression :/
I have been updating the rest of the .ll after I "fixed" the infinite loop. And, it doesn't look so good.
I will try the larger pattern and let's see what the result is.

SDValue A;
SDValue B;
APInt Cst;
if (sd_match(N, m_Xor(m_Or(m_Value(A), m_Value(B)), m_ConstInt(Cst))) &&
Cst.isAllOnes()) {
auto Ty = N->getValueType(0);
return DAG.getNode(
ISD::AND, DL, VT,
DAG.getNode(ISD::XOR, DL, VT, A, DAG.getConstant(Cst, DL, Ty)),
DAG.getNode(ISD::XOR, DL, VT, B, DAG.getConstant(Cst, DL, Ty)));
}
}

return SDValue();
}

Expand Down
184 changes: 116 additions & 68 deletions llvm/test/CodeGen/X86/andnot-patterns.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -761,6 +761,7 @@ define i64 @andnot_bitreverse_i64(i64 %a0, i64 %a1) nounwind {
;
; X86-BMI-LABEL: andnot_bitreverse_i64:
; X86-BMI: # %bb.0:
; X86-BMI-NEXT: pushl %esi
; X86-BMI-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-BMI-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-BMI-NEXT: bswapl %eax
Expand All @@ -774,13 +775,16 @@ define i64 @andnot_bitreverse_i64(i64 %a0, i64 %a1) nounwind {
; X86-BMI-NEXT: andl $858993459, %edx # imm = 0x33333333
; X86-BMI-NEXT: shrl $2, %eax
; X86-BMI-NEXT: andl $858993459, %eax # imm = 0x33333333
; X86-BMI-NEXT: leal (%eax,%edx,4), %eax
; X86-BMI-NEXT: movl %eax, %edx
; X86-BMI-NEXT: andl $1431655765, %edx # imm = 0x55555555
; X86-BMI-NEXT: leal (%eax,%edx,4), %esi
; X86-BMI-NEXT: andl $1431655765, %esi # imm = 0x55555555
; X86-BMI-NEXT: addl %esi, %esi
; X86-BMI-NEXT: shll $2, %edx
; X86-BMI-NEXT: notl %edx
; X86-BMI-NEXT: andnl %edx, %eax, %eax
; X86-BMI-NEXT: shrl %eax
; X86-BMI-NEXT: andl $1431655765, %eax # imm = 0x55555555
; X86-BMI-NEXT: leal (%eax,%edx,2), %eax
; X86-BMI-NEXT: andnl {{[0-9]+}}(%esp), %eax, %eax
; X86-BMI-NEXT: orl $-1431655766, %eax # imm = 0xAAAAAAAA
; X86-BMI-NEXT: andnl %eax, %esi, %eax
; X86-BMI-NEXT: andl {{[0-9]+}}(%esp), %eax
; X86-BMI-NEXT: bswapl %ecx
; X86-BMI-NEXT: movl %ecx, %edx
; X86-BMI-NEXT: andl $252645135, %edx # imm = 0xF0F0F0F
Expand All @@ -792,13 +796,17 @@ define i64 @andnot_bitreverse_i64(i64 %a0, i64 %a1) nounwind {
; X86-BMI-NEXT: andl $858993459, %edx # imm = 0x33333333
; X86-BMI-NEXT: shrl $2, %ecx
; X86-BMI-NEXT: andl $858993459, %ecx # imm = 0x33333333
; X86-BMI-NEXT: leal (%ecx,%edx,4), %ecx
; X86-BMI-NEXT: movl %ecx, %edx
; X86-BMI-NEXT: andl $1431655765, %edx # imm = 0x55555555
; X86-BMI-NEXT: leal (%ecx,%edx,4), %esi
; X86-BMI-NEXT: andl $1431655765, %esi # imm = 0x55555555
; X86-BMI-NEXT: addl %esi, %esi
; X86-BMI-NEXT: shll $2, %edx
; X86-BMI-NEXT: notl %edx
; X86-BMI-NEXT: andnl %edx, %ecx, %ecx
; X86-BMI-NEXT: shrl %ecx
; X86-BMI-NEXT: andl $1431655765, %ecx # imm = 0x55555555
; X86-BMI-NEXT: leal (%ecx,%edx,2), %ecx
; X86-BMI-NEXT: andnl {{[0-9]+}}(%esp), %ecx, %edx
; X86-BMI-NEXT: orl $-1431655766, %ecx # imm = 0xAAAAAAAA
; X86-BMI-NEXT: andnl %ecx, %esi, %edx
; X86-BMI-NEXT: andl {{[0-9]+}}(%esp), %edx
; X86-BMI-NEXT: popl %esi
; X86-BMI-NEXT: retl
;
; X64-NOBMI-LABEL: andnot_bitreverse_i64:
Expand Down Expand Up @@ -837,19 +845,23 @@ define i64 @andnot_bitreverse_i64(i64 %a0, i64 %a1) nounwind {
; X64-BMI-NEXT: andq %rcx, %rsi
; X64-BMI-NEXT: shlq $4, %rsi
; X64-BMI-NEXT: orq %rax, %rsi
; X64-BMI-NEXT: movabsq $3689348814741910323, %rax # imm = 0x3333333333333333
; X64-BMI-NEXT: movq %rsi, %rcx
; X64-BMI-NEXT: andq %rax, %rcx
; X64-BMI-NEXT: shrq $2, %rsi
; X64-BMI-NEXT: andq %rax, %rsi
; X64-BMI-NEXT: leaq (%rsi,%rcx,4), %rax
; X64-BMI-NEXT: movabsq $6148914691236517205, %rcx # imm = 0x5555555555555555
; X64-BMI-NEXT: movq %rax, %rdx
; X64-BMI-NEXT: andq %rcx, %rdx
; X64-BMI-NEXT: shrq %rax
; X64-BMI-NEXT: movq %rsi, %rax
; X64-BMI-NEXT: shrq $2, %rax
; X64-BMI-NEXT: movabsq $3689348814741910323, %rcx # imm = 0x3333333333333333
; X64-BMI-NEXT: andq %rcx, %rax
; X64-BMI-NEXT: leaq (%rax,%rdx,2), %rax
; X64-BMI-NEXT: andnq %rdi, %rax, %rax
; X64-BMI-NEXT: andq %rcx, %rsi
; X64-BMI-NEXT: leaq (,%rsi,4), %rcx
; X64-BMI-NEXT: notq %rcx
; X64-BMI-NEXT: andnq %rcx, %rax, %rcx
; X64-BMI-NEXT: shrq %rcx
; X64-BMI-NEXT: movabsq $-6148914691236517206, %rdx # imm = 0xAAAAAAAAAAAAAAAA
; X64-BMI-NEXT: orq %rcx, %rdx
; X64-BMI-NEXT: leaq (%rax,%rsi,4), %rax
; X64-BMI-NEXT: movabsq $6148914691236517205, %rcx # imm = 0x5555555555555555
; X64-BMI-NEXT: andq %rax, %rcx
; X64-BMI-NEXT: addq %rcx, %rcx
; X64-BMI-NEXT: andnq %rdx, %rcx, %rax
; X64-BMI-NEXT: andq %rdi, %rax
; X64-BMI-NEXT: retq
%not = xor i64 %a1, -1
%bitrev = tail call i64 @llvm.bitreverse.i64(i64 %not)
Expand Down Expand Up @@ -896,13 +908,16 @@ define i32 @andnot_bitreverse_i32(i32 %a0, i32 %a1) nounwind {
; X86-BMI-NEXT: andl $858993459, %ecx # imm = 0x33333333
; X86-BMI-NEXT: shrl $2, %eax
; X86-BMI-NEXT: andl $858993459, %eax # imm = 0x33333333
; X86-BMI-NEXT: leal (%eax,%ecx,4), %eax
; X86-BMI-NEXT: movl %eax, %ecx
; X86-BMI-NEXT: andl $1431655765, %ecx # imm = 0x55555555
; X86-BMI-NEXT: leal (%eax,%ecx,4), %edx
; X86-BMI-NEXT: andl $1431655765, %edx # imm = 0x55555555
; X86-BMI-NEXT: addl %edx, %edx
; X86-BMI-NEXT: shll $2, %ecx
; X86-BMI-NEXT: notl %ecx
; X86-BMI-NEXT: andnl %ecx, %eax, %eax
; X86-BMI-NEXT: shrl %eax
; X86-BMI-NEXT: andl $1431655765, %eax # imm = 0x55555555
; X86-BMI-NEXT: leal (%eax,%ecx,2), %eax
; X86-BMI-NEXT: andnl {{[0-9]+}}(%esp), %eax, %eax
; X86-BMI-NEXT: orl $-1431655766, %eax # imm = 0xAAAAAAAA
; X86-BMI-NEXT: andnl %eax, %edx, %eax
; X86-BMI-NEXT: andl {{[0-9]+}}(%esp), %eax
; X86-BMI-NEXT: retl
;
; X64-NOBMI-LABEL: andnot_bitreverse_i32:
Expand Down Expand Up @@ -940,16 +955,19 @@ define i32 @andnot_bitreverse_i32(i32 %a0, i32 %a1) nounwind {
; X64-BMI-NEXT: andl $252645135, %esi # imm = 0xF0F0F0F
; X64-BMI-NEXT: orl %eax, %esi
; X64-BMI-NEXT: movl %esi, %eax
; X64-BMI-NEXT: shrl $2, %eax
; X64-BMI-NEXT: andl $858993459, %eax # imm = 0x33333333
; X64-BMI-NEXT: shrl $2, %esi
; X64-BMI-NEXT: andl $858993459, %esi # imm = 0x33333333
; X64-BMI-NEXT: leal (%rsi,%rax,4), %eax
; X64-BMI-NEXT: movl %eax, %ecx
; X64-BMI-NEXT: andl $1431655765, %ecx # imm = 0x55555555
; X64-BMI-NEXT: shrl %eax
; X64-BMI-NEXT: leal (,%rsi,4), %ecx
; X64-BMI-NEXT: notl %ecx
; X64-BMI-NEXT: andnl %ecx, %eax, %ecx
; X64-BMI-NEXT: shrl %ecx
; X64-BMI-NEXT: orl $-1431655766, %ecx # imm = 0xAAAAAAAA
; X64-BMI-NEXT: leal (%rax,%rsi,4), %eax
; X64-BMI-NEXT: andl $1431655765, %eax # imm = 0x55555555
; X64-BMI-NEXT: leal (%rax,%rcx,2), %eax
; X64-BMI-NEXT: andnl %edi, %eax, %eax
; X64-BMI-NEXT: addl %eax, %eax
; X64-BMI-NEXT: andnl %ecx, %eax, %eax
; X64-BMI-NEXT: andl %edi, %eax
; X64-BMI-NEXT: retq
%not = xor i32 %a1, -1
%bitrev = tail call i32 @llvm.bitreverse.i32(i32 %not)
Expand All @@ -958,30 +976,57 @@ define i32 @andnot_bitreverse_i32(i32 %a0, i32 %a1) nounwind {
}

define i16 @andnot_bitreverse_i16(i16 %a0, i16 %a1) nounwind {
; X86-LABEL: andnot_bitreverse_i16:
; X86: # %bb.0:
; X86-NEXT: movzwl {{[0-9]+}}(%esp), %eax
; X86-NEXT: rolw $8, %ax
; X86-NEXT: movl %eax, %ecx
; X86-NEXT: andl $3855, %ecx # imm = 0xF0F
; X86-NEXT: shll $4, %ecx
; X86-NEXT: shrl $4, %eax
; X86-NEXT: andl $3855, %eax # imm = 0xF0F
; X86-NEXT: orl %ecx, %eax
; X86-NEXT: movl %eax, %ecx
; X86-NEXT: andl $13107, %ecx # imm = 0x3333
; X86-NEXT: shrl $2, %eax
; X86-NEXT: andl $13107, %eax # imm = 0x3333
; X86-NEXT: leal (%eax,%ecx,4), %eax
; X86-NEXT: movl %eax, %ecx
; X86-NEXT: andl $21845, %ecx # imm = 0x5555
; X86-NEXT: shrl %eax
; X86-NEXT: andl $21845, %eax # imm = 0x5555
; X86-NEXT: leal (%eax,%ecx,2), %eax
; X86-NEXT: notl %eax
; X86-NEXT: andw {{[0-9]+}}(%esp), %ax
; X86-NEXT: # kill: def $ax killed $ax killed $eax
; X86-NEXT: retl
; X86-NOBMI-LABEL: andnot_bitreverse_i16:
; X86-NOBMI: # %bb.0:
; X86-NOBMI-NEXT: movzwl {{[0-9]+}}(%esp), %eax
; X86-NOBMI-NEXT: rolw $8, %ax
; X86-NOBMI-NEXT: movl %eax, %ecx
; X86-NOBMI-NEXT: andl $3855, %ecx # imm = 0xF0F
; X86-NOBMI-NEXT: shll $4, %ecx
; X86-NOBMI-NEXT: shrl $4, %eax
; X86-NOBMI-NEXT: andl $3855, %eax # imm = 0xF0F
; X86-NOBMI-NEXT: orl %ecx, %eax
; X86-NOBMI-NEXT: movl %eax, %ecx
; X86-NOBMI-NEXT: andl $13107, %ecx # imm = 0x3333
; X86-NOBMI-NEXT: shrl $2, %eax
; X86-NOBMI-NEXT: andl $13107, %eax # imm = 0x3333
; X86-NOBMI-NEXT: leal (%eax,%ecx,4), %eax
; X86-NOBMI-NEXT: movl %eax, %ecx
; X86-NOBMI-NEXT: andl $21845, %ecx # imm = 0x5555
; X86-NOBMI-NEXT: shrl %eax
; X86-NOBMI-NEXT: andl $21845, %eax # imm = 0x5555
; X86-NOBMI-NEXT: leal (%eax,%ecx,2), %eax
; X86-NOBMI-NEXT: notl %eax
; X86-NOBMI-NEXT: andw {{[0-9]+}}(%esp), %ax
; X86-NOBMI-NEXT: # kill: def $ax killed $ax killed $eax
; X86-NOBMI-NEXT: retl
;
; X86-BMI-LABEL: andnot_bitreverse_i16:
; X86-BMI: # %bb.0:
; X86-BMI-NEXT: movzwl {{[0-9]+}}(%esp), %eax
; X86-BMI-NEXT: rolw $8, %ax
; X86-BMI-NEXT: movl %eax, %ecx
; X86-BMI-NEXT: andl $3855, %ecx # imm = 0xF0F
; X86-BMI-NEXT: shll $4, %ecx
; X86-BMI-NEXT: shrl $4, %eax
; X86-BMI-NEXT: andl $3855, %eax # imm = 0xF0F
; X86-BMI-NEXT: orl %ecx, %eax
; X86-BMI-NEXT: movl %eax, %ecx
; X86-BMI-NEXT: andl $13107, %ecx # imm = 0x3333
; X86-BMI-NEXT: shrl $2, %eax
; X86-BMI-NEXT: andl $13107, %eax # imm = 0x3333
; X86-BMI-NEXT: leal (%eax,%ecx,4), %edx
; X86-BMI-NEXT: andl $21845, %edx # imm = 0x5555
; X86-BMI-NEXT: addl %edx, %edx
; X86-BMI-NEXT: shll $2, %ecx
; X86-BMI-NEXT: notl %ecx
; X86-BMI-NEXT: andnl %ecx, %eax, %eax
; X86-BMI-NEXT: shrl %eax
; X86-BMI-NEXT: orl $43690, %eax # imm = 0xAAAA
; X86-BMI-NEXT: andnl %eax, %edx, %eax
; X86-BMI-NEXT: andw {{[0-9]+}}(%esp), %ax
; X86-BMI-NEXT: # kill: def $ax killed $ax killed $eax
; X86-BMI-NEXT: retl
;
; X64-NOBMI-LABEL: andnot_bitreverse_i16:
; X64-NOBMI: # %bb.0:
Expand Down Expand Up @@ -1019,16 +1064,19 @@ define i16 @andnot_bitreverse_i16(i16 %a0, i16 %a1) nounwind {
; X64-BMI-NEXT: andl $3855, %esi # imm = 0xF0F
; X64-BMI-NEXT: orl %eax, %esi
; X64-BMI-NEXT: movl %esi, %eax
; X64-BMI-NEXT: shrl $2, %eax
; X64-BMI-NEXT: andl $13107, %eax # imm = 0x3333
; X64-BMI-NEXT: shrl $2, %esi
; X64-BMI-NEXT: andl $13107, %esi # imm = 0x3333
; X64-BMI-NEXT: leal (%rsi,%rax,4), %eax
; X64-BMI-NEXT: movl %eax, %ecx
; X64-BMI-NEXT: andl $21845, %ecx # imm = 0x5555
; X64-BMI-NEXT: shrl %eax
; X64-BMI-NEXT: leal (,%rsi,4), %ecx
; X64-BMI-NEXT: notl %ecx
; X64-BMI-NEXT: andnl %ecx, %eax, %ecx
; X64-BMI-NEXT: shrl %ecx
; X64-BMI-NEXT: orl $-21846, %ecx # imm = 0xAAAA
; X64-BMI-NEXT: leal (%rax,%rsi,4), %eax
; X64-BMI-NEXT: andl $21845, %eax # imm = 0x5555
; X64-BMI-NEXT: leal (%rax,%rcx,2), %eax
; X64-BMI-NEXT: andnl %edi, %eax, %eax
; X64-BMI-NEXT: addl %eax, %eax
; X64-BMI-NEXT: andnl %ecx, %eax, %eax
; X64-BMI-NEXT: andl %edi, %eax
; X64-BMI-NEXT: # kill: def $ax killed $ax killed $eax
; X64-BMI-NEXT: retq
%not = xor i16 %a1, -1
Expand Down
Loading
Loading