[llvm] [DAG] Fold (and X, (bswap/bitreverse (not Y))) -> (and X, (not (bswap/bitreverse Y))) on ANDNOT capable targets (PR #112547)
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Wed Oct 16 07:01:56 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-x86
Author: Simon Pilgrim (RKSimon)
<details>
<summary>Changes</summary>
Fixes #<!-- -->112425
---
Full diff: https://github.com/llvm/llvm-project/pull/112547.diff
2 Files Affected:
- (modified) llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (+15)
- (modified) llvm/test/CodeGen/X86/andnot-patterns.ll (+32-44)
``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index ca91d35573c3ec..7c2d840e48515b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7350,6 +7350,21 @@ SDValue DAGCombiner::visitAND(SDNode *N) {
if (SDValue R = foldLogicOfShifts(N, N1, N0, DAG))
return R;
+ // If the target supports ANDNOT, attempt to reconstruct an ANDNOT pattern
+ // that might have become separated by a bitwise-agnostic instruction.
+ if (TLI.hasAndNot(SDValue(N, 0))) {
+ SDValue X, Y;
+
+ // Fold (and X, (bswap (not Y))) -> (and X, (not (bswap Y)))
+ // Fold (and X, (bitreverse (not Y))) -> (and X, (not (bitreverse Y)))
+ for (unsigned Opc : {ISD::BSWAP, ISD::BITREVERSE})
+ if (sd_match(N, m_And(m_Value(X),
+ m_OneUse(m_UnaryOp(Opc, m_Not(m_Value(Y)))))) &&
+ !sd_match(X, m_Not(m_Value())))
+ return DAG.getNode(ISD::AND, DL, VT, X,
+ DAG.getNOT(DL, DAG.getNode(Opc, DL, VT, Y), VT));
+ }
+
// Masking the negated extension of a boolean is just the zero-extended
// boolean:
// and (sub 0, zext(bool X)), 1 --> zext(bool X)
diff --git a/llvm/test/CodeGen/X86/andnot-patterns.ll b/llvm/test/CodeGen/X86/andnot-patterns.ll
index 46ebe6ba76567a..47d1d69f4ea357 100644
--- a/llvm/test/CodeGen/X86/andnot-patterns.ll
+++ b/llvm/test/CodeGen/X86/andnot-patterns.ll
@@ -321,22 +321,18 @@ define i8 @andnot_rotr_i8(i8 %a0, i8 %a1, i8 %a2) nounwind {
define i64 @andnot_bswap_i64(i64 %a0, i64 %a1) nounwind {
; X86-LABEL: andnot_bswap_i64:
; X86: # %bb.0:
-; X86-NEXT: movl {{[0-9]+}}(%esp), %edx
+; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: notl %eax
-; X86-NEXT: notl %edx
-; X86-NEXT: bswapl %edx
; X86-NEXT: bswapl %eax
-; X86-NEXT: andl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: andl {{[0-9]+}}(%esp), %edx
+; X86-NEXT: andnl {{[0-9]+}}(%esp), %eax, %eax
+; X86-NEXT: bswapl %ecx
+; X86-NEXT: andnl {{[0-9]+}}(%esp), %ecx, %edx
; X86-NEXT: retl
;
; X64-LABEL: andnot_bswap_i64:
; X64: # %bb.0:
-; X64-NEXT: movq %rsi, %rax
-; X64-NEXT: notq %rax
-; X64-NEXT: bswapq %rax
-; X64-NEXT: andq %rdi, %rax
+; X64-NEXT: bswapq %rsi
+; X64-NEXT: andnq %rdi, %rsi, %rax
; X64-NEXT: retq
%not = xor i64 %a1, -1
%bswap = tail call i64 @llvm.bswap.i64(i64 %not)
@@ -348,17 +344,14 @@ define i32 @andnot_bswap_i32(i32 %a0, i32 %a1) nounwind {
; X86-LABEL: andnot_bswap_i32:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: notl %eax
; X86-NEXT: bswapl %eax
-; X86-NEXT: andl {{[0-9]+}}(%esp), %eax
+; X86-NEXT: andnl {{[0-9]+}}(%esp), %eax, %eax
; X86-NEXT: retl
;
; X64-LABEL: andnot_bswap_i32:
; X64: # %bb.0:
-; X64-NEXT: movl %esi, %eax
-; X64-NEXT: notl %eax
-; X64-NEXT: bswapl %eax
-; X64-NEXT: andl %edi, %eax
+; X64-NEXT: bswapl %esi
+; X64-NEXT: andnl %edi, %esi, %eax
; X64-NEXT: retq
%not = xor i32 %a1, -1
%bswap = tail call i32 @llvm.bswap.i32(i32 %not)
@@ -399,8 +392,24 @@ define i64 @andnot_bitreverse_i64(i64 %a0, i64 %a1) nounwind {
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: notl %eax
-; X86-NEXT: notl %ecx
+; X86-NEXT: bswapl %eax
+; X86-NEXT: movl %eax, %edx
+; X86-NEXT: andl $252645135, %edx # imm = 0xF0F0F0F
+; X86-NEXT: shll $4, %edx
+; X86-NEXT: shrl $4, %eax
+; X86-NEXT: andl $252645135, %eax # imm = 0xF0F0F0F
+; X86-NEXT: orl %edx, %eax
+; X86-NEXT: movl %eax, %edx
+; X86-NEXT: andl $858993459, %edx # imm = 0x33333333
+; X86-NEXT: shrl $2, %eax
+; X86-NEXT: andl $858993459, %eax # imm = 0x33333333
+; X86-NEXT: leal (%eax,%edx,4), %eax
+; X86-NEXT: movl %eax, %edx
+; X86-NEXT: andl $1431655765, %edx # imm = 0x55555555
+; X86-NEXT: shrl %eax
+; X86-NEXT: andl $1431655765, %eax # imm = 0x55555555
+; X86-NEXT: leal (%eax,%edx,2), %eax
+; X86-NEXT: andnl {{[0-9]+}}(%esp), %eax, %eax
; X86-NEXT: bswapl %ecx
; X86-NEXT: movl %ecx, %edx
; X86-NEXT: andl $252645135, %edx # imm = 0xF0F0F0F
@@ -417,31 +426,12 @@ define i64 @andnot_bitreverse_i64(i64 %a0, i64 %a1) nounwind {
; X86-NEXT: andl $1431655765, %edx # imm = 0x55555555
; X86-NEXT: shrl %ecx
; X86-NEXT: andl $1431655765, %ecx # imm = 0x55555555
-; X86-NEXT: leal (%ecx,%edx,2), %edx
-; X86-NEXT: bswapl %eax
-; X86-NEXT: movl %eax, %ecx
-; X86-NEXT: andl $252645135, %ecx # imm = 0xF0F0F0F
-; X86-NEXT: shll $4, %ecx
-; X86-NEXT: shrl $4, %eax
-; X86-NEXT: andl $252645135, %eax # imm = 0xF0F0F0F
-; X86-NEXT: orl %ecx, %eax
-; X86-NEXT: movl %eax, %ecx
-; X86-NEXT: andl $858993459, %ecx # imm = 0x33333333
-; X86-NEXT: shrl $2, %eax
-; X86-NEXT: andl $858993459, %eax # imm = 0x33333333
-; X86-NEXT: leal (%eax,%ecx,4), %eax
-; X86-NEXT: movl %eax, %ecx
-; X86-NEXT: andl $1431655765, %ecx # imm = 0x55555555
-; X86-NEXT: shrl %eax
-; X86-NEXT: andl $1431655765, %eax # imm = 0x55555555
-; X86-NEXT: leal (%eax,%ecx,2), %eax
-; X86-NEXT: andl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: andl {{[0-9]+}}(%esp), %edx
+; X86-NEXT: leal (%ecx,%edx,2), %ecx
+; X86-NEXT: andnl {{[0-9]+}}(%esp), %ecx, %edx
; X86-NEXT: retl
;
; X64-LABEL: andnot_bitreverse_i64:
; X64: # %bb.0:
-; X64-NEXT: notq %rsi
; X64-NEXT: bswapq %rsi
; X64-NEXT: movq %rsi, %rax
; X64-NEXT: shrq $4, %rax
@@ -462,7 +452,7 @@ define i64 @andnot_bitreverse_i64(i64 %a0, i64 %a1) nounwind {
; X64-NEXT: shrq %rax
; X64-NEXT: andq %rcx, %rax
; X64-NEXT: leaq (%rax,%rdx,2), %rax
-; X64-NEXT: andq %rdi, %rax
+; X64-NEXT: andnq %rdi, %rax, %rax
; X64-NEXT: retq
%not = xor i64 %a1, -1
%bitrev = tail call i64 @llvm.bitreverse.i64(i64 %not)
@@ -474,7 +464,6 @@ define i32 @andnot_bitreverse_i32(i32 %a0, i32 %a1) nounwind {
; X86-LABEL: andnot_bitreverse_i32:
; X86: # %bb.0:
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
-; X86-NEXT: notl %eax
; X86-NEXT: bswapl %eax
; X86-NEXT: movl %eax, %ecx
; X86-NEXT: andl $252645135, %ecx # imm = 0xF0F0F0F
@@ -492,13 +481,12 @@ define i32 @andnot_bitreverse_i32(i32 %a0, i32 %a1) nounwind {
; X86-NEXT: shrl %eax
; X86-NEXT: andl $1431655765, %eax # imm = 0x55555555
; X86-NEXT: leal (%eax,%ecx,2), %eax
-; X86-NEXT: andl {{[0-9]+}}(%esp), %eax
+; X86-NEXT: andnl {{[0-9]+}}(%esp), %eax, %eax
; X86-NEXT: retl
;
; X64-LABEL: andnot_bitreverse_i32:
; X64: # %bb.0:
; X64-NEXT: # kill: def $esi killed $esi def $rsi
-; X64-NEXT: notl %esi
; X64-NEXT: bswapl %esi
; X64-NEXT: movl %esi, %eax
; X64-NEXT: andl $252645135, %eax # imm = 0xF0F0F0F
@@ -516,7 +504,7 @@ define i32 @andnot_bitreverse_i32(i32 %a0, i32 %a1) nounwind {
; X64-NEXT: shrl %eax
; X64-NEXT: andl $1431655765, %eax # imm = 0x55555555
; X64-NEXT: leal (%rax,%rcx,2), %eax
-; X64-NEXT: andl %edi, %eax
+; X64-NEXT: andnl %edi, %eax, %eax
; X64-NEXT: retq
%not = xor i32 %a1, -1
%bitrev = tail call i32 @llvm.bitreverse.i32(i32 %not)
``````````
</details>
https://github.com/llvm/llvm-project/pull/112547
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