[llvm-branch-commits] [llvm] e7dc53b - [Mips] In LowerShift*Parts, xor with bits-1 instead of -1. (#71149)
Tobias Hieta via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Mon Nov 13 01:51:43 PST 2023
Author: Craig Topper
Date: 2023-11-13T10:50:48+01:00
New Revision: e7dc53b94212b2a65f9fb995fd3e0f9a2d192fdc
URL: https://github.com/llvm/llvm-project/commit/e7dc53b94212b2a65f9fb995fd3e0f9a2d192fdc
DIFF: https://github.com/llvm/llvm-project/commit/e7dc53b94212b2a65f9fb995fd3e0f9a2d192fdc.diff
LOG: [Mips] In LowerShift*Parts, xor with bits-1 instead of -1. (#71149)
If we start with an i128 shift, the initial shift amount would usually
have zeros in bit 8 and above. xoring the shift amount with -1 will set
those upper bits to 1. If DAGCombiner is able to prove those bits are
now 1, then the shift that uses the xor will be replaced with undef.
Which we don't want.
Reduce the xor constant to VT.bits-1 where VT is half the size of the
larger shift type. This avoids toggling the upper bits. The hardware
shift instruction only uses the lower bits of the shift amount. I assume
the code used NOT because the hardware doesn't use the upper bits, but
that isn't compatible with the LLVM poison semantics.
Fixes #71142.
(cherry picked from commit 8d24d3900ec3f28902b2fad4a2c2c2b789257424)
Added:
Modified:
llvm/lib/Target/Mips/MipsISelLowering.cpp
llvm/test/CodeGen/Mips/llvm-ir/ashr.ll
llvm/test/CodeGen/Mips/llvm-ir/lshr.ll
llvm/test/CodeGen/Mips/llvm-ir/shl.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/Mips/MipsISelLowering.cpp b/llvm/lib/Target/Mips/MipsISelLowering.cpp
index 18d7773067f1378..3c69ec4912b1e60 100644
--- a/llvm/lib/Target/Mips/MipsISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsISelLowering.cpp
@@ -2593,12 +2593,13 @@ SDValue MipsTargetLowering::lowerShiftLeftParts(SDValue Op,
SDValue Shamt = Op.getOperand(2);
// if shamt < (VT.bits):
// lo = (shl lo, shamt)
- // hi = (or (shl hi, shamt) (srl (srl lo, 1), ~shamt))
+ // hi = (or (shl hi, shamt) (srl (srl lo, 1), (xor shamt, (VT.bits-1))))
// else:
// lo = 0
// hi = (shl lo, shamt[4:0])
- SDValue Not = DAG.getNode(ISD::XOR, DL, MVT::i32, Shamt,
- DAG.getConstant(-1, DL, MVT::i32));
+ SDValue Not =
+ DAG.getNode(ISD::XOR, DL, MVT::i32, Shamt,
+ DAG.getConstant(VT.getSizeInBits() - 1, DL, MVT::i32));
SDValue ShiftRight1Lo = DAG.getNode(ISD::SRL, DL, VT, Lo,
DAG.getConstant(1, DL, VT));
SDValue ShiftRightLo = DAG.getNode(ISD::SRL, DL, VT, ShiftRight1Lo, Not);
@@ -2623,7 +2624,7 @@ SDValue MipsTargetLowering::lowerShiftRightParts(SDValue Op, SelectionDAG &DAG,
MVT VT = Subtarget.isGP64bit() ? MVT::i64 : MVT::i32;
// if shamt < (VT.bits):
- // lo = (or (shl (shl hi, 1), ~shamt) (srl lo, shamt))
+ // lo = (or (shl (shl hi, 1), (xor shamt, (VT.bits-1))) (srl lo, shamt))
// if isSRA:
// hi = (sra hi, shamt)
// else:
@@ -2635,8 +2636,9 @@ SDValue MipsTargetLowering::lowerShiftRightParts(SDValue Op, SelectionDAG &DAG,
// else:
// lo = (srl hi, shamt[4:0])
// hi = 0
- SDValue Not = DAG.getNode(ISD::XOR, DL, MVT::i32, Shamt,
- DAG.getConstant(-1, DL, MVT::i32));
+ SDValue Not =
+ DAG.getNode(ISD::XOR, DL, MVT::i32, Shamt,
+ DAG.getConstant(VT.getSizeInBits() - 1, DL, MVT::i32));
SDValue ShiftLeft1Hi = DAG.getNode(ISD::SHL, DL, VT, Hi,
DAG.getConstant(1, DL, VT));
SDValue ShiftLeftHi = DAG.getNode(ISD::SHL, DL, VT, ShiftLeft1Hi, Not);
diff --git a/llvm/test/CodeGen/Mips/llvm-ir/ashr.ll b/llvm/test/CodeGen/Mips/llvm-ir/ashr.ll
index 47d18b9b5c533e9..453ca0d6bab3b18 100644
--- a/llvm/test/CodeGen/Mips/llvm-ir/ashr.ll
+++ b/llvm/test/CodeGen/Mips/llvm-ir/ashr.ll
@@ -280,7 +280,7 @@ define signext i64 @ashr_i64(i64 signext %a, i64 signext %b) {
; MIPS-NEXT: srav $3, $4, $7
; MIPS-NEXT: # %bb.1: # %entry
; MIPS-NEXT: srlv $1, $5, $7
-; MIPS-NEXT: not $2, $7
+; MIPS-NEXT: xori $2, $7, 31
; MIPS-NEXT: sll $4, $4, 1
; MIPS-NEXT: sllv $2, $4, $2
; MIPS-NEXT: or $1, $2, $1
@@ -294,7 +294,7 @@ define signext i64 @ashr_i64(i64 signext %a, i64 signext %b) {
; MIPS32-LABEL: ashr_i64:
; MIPS32: # %bb.0: # %entry
; MIPS32-NEXT: srlv $1, $5, $7
-; MIPS32-NEXT: not $2, $7
+; MIPS32-NEXT: xori $2, $7, 31
; MIPS32-NEXT: sll $3, $4, 1
; MIPS32-NEXT: sllv $2, $3, $2
; MIPS32-NEXT: or $3, $2, $1
@@ -308,7 +308,7 @@ define signext i64 @ashr_i64(i64 signext %a, i64 signext %b) {
; 32R2-LABEL: ashr_i64:
; 32R2: # %bb.0: # %entry
; 32R2-NEXT: srlv $1, $5, $7
-; 32R2-NEXT: not $2, $7
+; 32R2-NEXT: xori $2, $7, 31
; 32R2-NEXT: sll $3, $4, 1
; 32R2-NEXT: sllv $2, $3, $2
; 32R2-NEXT: or $3, $2, $1
@@ -328,7 +328,7 @@ define signext i64 @ashr_i64(i64 signext %a, i64 signext %b) {
; 32R6-NEXT: selnez $6, $6, $3
; 32R6-NEXT: or $2, $6, $2
; 32R6-NEXT: srlv $5, $5, $7
-; 32R6-NEXT: not $6, $7
+; 32R6-NEXT: xori $6, $7, 31
; 32R6-NEXT: sll $4, $4, 1
; 32R6-NEXT: sllv $4, $4, $6
; 32R6-NEXT: or $4, $4, $5
@@ -360,9 +360,9 @@ define signext i64 @ashr_i64(i64 signext %a, i64 signext %b) {
; MMR3-LABEL: ashr_i64:
; MMR3: # %bb.0: # %entry
; MMR3-NEXT: srlv $2, $5, $7
-; MMR3-NEXT: not16 $3, $7
-; MMR3-NEXT: sll16 $5, $4, 1
-; MMR3-NEXT: sllv $3, $5, $3
+; MMR3-NEXT: xori $1, $7, 31
+; MMR3-NEXT: sll16 $3, $4, 1
+; MMR3-NEXT: sllv $3, $3, $1
; MMR3-NEXT: or16 $3, $2
; MMR3-NEXT: srav $2, $4, $7
; MMR3-NEXT: andi16 $5, $7, 32
@@ -380,7 +380,7 @@ define signext i64 @ashr_i64(i64 signext %a, i64 signext %b) {
; MMR6-NEXT: selnez $6, $6, $3
; MMR6-NEXT: or $2, $6, $2
; MMR6-NEXT: srlv $5, $5, $7
-; MMR6-NEXT: not16 $6, $7
+; MMR6-NEXT: xori $6, $7, 31
; MMR6-NEXT: sll16 $4, $4, 1
; MMR6-NEXT: sllv $4, $4, $6
; MMR6-NEXT: or $4, $4, $5
@@ -609,7 +609,7 @@ define signext i128 @ashr_i128(i128 signext %a, i128 signext %b) {
; MIPS3-NEXT: # %bb.1: # %entry
; MIPS3-NEXT: dsrlv $1, $5, $7
; MIPS3-NEXT: dsll $4, $4, 1
-; MIPS3-NEXT: not $2, $2
+; MIPS3-NEXT: xori $2, $2, 63
; MIPS3-NEXT: dsllv $2, $4, $2
; MIPS3-NEXT: or $1, $2, $1
; MIPS3-NEXT: move $2, $3
@@ -624,7 +624,7 @@ define signext i128 @ashr_i128(i128 signext %a, i128 signext %b) {
; MIPS64-NEXT: dsrlv $1, $5, $7
; MIPS64-NEXT: dsll $2, $4, 1
; MIPS64-NEXT: sll $5, $7, 0
-; MIPS64-NEXT: not $3, $5
+; MIPS64-NEXT: xori $3, $5, 63
; MIPS64-NEXT: dsllv $2, $2, $3
; MIPS64-NEXT: or $3, $2, $1
; MIPS64-NEXT: dsrav $2, $4, $7
@@ -639,7 +639,7 @@ define signext i128 @ashr_i128(i128 signext %a, i128 signext %b) {
; MIPS64R2-NEXT: dsrlv $1, $5, $7
; MIPS64R2-NEXT: dsll $2, $4, 1
; MIPS64R2-NEXT: sll $5, $7, 0
-; MIPS64R2-NEXT: not $3, $5
+; MIPS64R2-NEXT: xori $3, $5, 63
; MIPS64R2-NEXT: dsllv $2, $2, $3
; MIPS64R2-NEXT: or $3, $2, $1
; MIPS64R2-NEXT: dsrav $2, $4, $7
@@ -661,7 +661,7 @@ define signext i128 @ashr_i128(i128 signext %a, i128 signext %b) {
; MIPS64R6-NEXT: or $2, $8, $2
; MIPS64R6-NEXT: dsrlv $5, $5, $7
; MIPS64R6-NEXT: dsll $4, $4, 1
-; MIPS64R6-NEXT: not $3, $3
+; MIPS64R6-NEXT: xori $3, $3, 63
; MIPS64R6-NEXT: dsllv $3, $4, $3
; MIPS64R6-NEXT: or $3, $3, $5
; MIPS64R6-NEXT: seleqz $3, $3, $6
diff --git a/llvm/test/CodeGen/Mips/llvm-ir/lshr.ll b/llvm/test/CodeGen/Mips/llvm-ir/lshr.ll
index c4e05117d28e15e..ddbb1f217837a46 100644
--- a/llvm/test/CodeGen/Mips/llvm-ir/lshr.ll
+++ b/llvm/test/CodeGen/Mips/llvm-ir/lshr.ll
@@ -283,7 +283,7 @@ define signext i64 @lshr_i64(i64 signext %a, i64 signext %b) {
; MIPS2-NEXT: addiu $2, $zero, 0
; MIPS2-NEXT: # %bb.1: # %entry
; MIPS2-NEXT: srlv $1, $5, $7
-; MIPS2-NEXT: not $2, $7
+; MIPS2-NEXT: xori $2, $7, 31
; MIPS2-NEXT: sll $3, $4, 1
; MIPS2-NEXT: sllv $2, $3, $2
; MIPS2-NEXT: or $3, $2, $1
@@ -296,7 +296,7 @@ define signext i64 @lshr_i64(i64 signext %a, i64 signext %b) {
; MIPS32-LABEL: lshr_i64:
; MIPS32: # %bb.0: # %entry
; MIPS32-NEXT: srlv $1, $5, $7
-; MIPS32-NEXT: not $2, $7
+; MIPS32-NEXT: xori $2, $7, 31
; MIPS32-NEXT: sll $3, $4, 1
; MIPS32-NEXT: sllv $2, $3, $2
; MIPS32-NEXT: or $3, $2, $1
@@ -309,7 +309,7 @@ define signext i64 @lshr_i64(i64 signext %a, i64 signext %b) {
; MIPS32R2-LABEL: lshr_i64:
; MIPS32R2: # %bb.0: # %entry
; MIPS32R2-NEXT: srlv $1, $5, $7
-; MIPS32R2-NEXT: not $2, $7
+; MIPS32R2-NEXT: xori $2, $7, 31
; MIPS32R2-NEXT: sll $3, $4, 1
; MIPS32R2-NEXT: sllv $2, $3, $2
; MIPS32R2-NEXT: or $3, $2, $1
@@ -322,7 +322,7 @@ define signext i64 @lshr_i64(i64 signext %a, i64 signext %b) {
; MIPS32R6-LABEL: lshr_i64:
; MIPS32R6: # %bb.0: # %entry
; MIPS32R6-NEXT: srlv $1, $5, $7
-; MIPS32R6-NEXT: not $2, $7
+; MIPS32R6-NEXT: xori $2, $7, 31
; MIPS32R6-NEXT: sll $3, $4, 1
; MIPS32R6-NEXT: sllv $2, $3, $2
; MIPS32R6-NEXT: or $1, $2, $1
@@ -362,9 +362,9 @@ define signext i64 @lshr_i64(i64 signext %a, i64 signext %b) {
; MMR3-LABEL: lshr_i64:
; MMR3: # %bb.0: # %entry
; MMR3-NEXT: srlv $2, $5, $7
-; MMR3-NEXT: not16 $3, $7
-; MMR3-NEXT: sll16 $5, $4, 1
-; MMR3-NEXT: sllv $3, $5, $3
+; MMR3-NEXT: xori $1, $7, 31
+; MMR3-NEXT: sll16 $3, $4, 1
+; MMR3-NEXT: sllv $3, $3, $1
; MMR3-NEXT: or16 $3, $2
; MMR3-NEXT: srlv $2, $4, $7
; MMR3-NEXT: andi16 $4, $7, 32
@@ -376,7 +376,7 @@ define signext i64 @lshr_i64(i64 signext %a, i64 signext %b) {
; MMR6-LABEL: lshr_i64:
; MMR6: # %bb.0: # %entry
; MMR6-NEXT: srlv $1, $5, $7
-; MMR6-NEXT: not16 $2, $7
+; MMR6-NEXT: xori $2, $7, 31
; MMR6-NEXT: sll16 $3, $4, 1
; MMR6-NEXT: sllv $2, $3, $2
; MMR6-NEXT: or $1, $2, $1
@@ -606,7 +606,7 @@ define signext i128 @lshr_i128(i128 signext %a, i128 signext %b) {
; MIPS3-NEXT: # %bb.1: # %entry
; MIPS3-NEXT: dsrlv $1, $5, $7
; MIPS3-NEXT: dsll $2, $4, 1
-; MIPS3-NEXT: not $3, $3
+; MIPS3-NEXT: xori $3, $3, 63
; MIPS3-NEXT: dsllv $2, $2, $3
; MIPS3-NEXT: or $3, $2, $1
; MIPS3-NEXT: jr $ra
@@ -620,7 +620,7 @@ define signext i128 @lshr_i128(i128 signext %a, i128 signext %b) {
; MIPS4-NEXT: dsrlv $1, $5, $7
; MIPS4-NEXT: dsll $2, $4, 1
; MIPS4-NEXT: sll $5, $7, 0
-; MIPS4-NEXT: not $3, $5
+; MIPS4-NEXT: xori $3, $5, 63
; MIPS4-NEXT: dsllv $2, $2, $3
; MIPS4-NEXT: or $3, $2, $1
; MIPS4-NEXT: dsrlv $2, $4, $7
@@ -634,7 +634,7 @@ define signext i128 @lshr_i128(i128 signext %a, i128 signext %b) {
; MIPS64-NEXT: dsrlv $1, $5, $7
; MIPS64-NEXT: dsll $2, $4, 1
; MIPS64-NEXT: sll $5, $7, 0
-; MIPS64-NEXT: not $3, $5
+; MIPS64-NEXT: xori $3, $5, 63
; MIPS64-NEXT: dsllv $2, $2, $3
; MIPS64-NEXT: or $3, $2, $1
; MIPS64-NEXT: dsrlv $2, $4, $7
@@ -648,7 +648,7 @@ define signext i128 @lshr_i128(i128 signext %a, i128 signext %b) {
; MIPS64R2-NEXT: dsrlv $1, $5, $7
; MIPS64R2-NEXT: dsll $2, $4, 1
; MIPS64R2-NEXT: sll $5, $7, 0
-; MIPS64R2-NEXT: not $3, $5
+; MIPS64R2-NEXT: xori $3, $5, 63
; MIPS64R2-NEXT: dsllv $2, $2, $3
; MIPS64R2-NEXT: or $3, $2, $1
; MIPS64R2-NEXT: dsrlv $2, $4, $7
@@ -662,7 +662,7 @@ define signext i128 @lshr_i128(i128 signext %a, i128 signext %b) {
; MIPS64R6-NEXT: dsrlv $1, $5, $7
; MIPS64R6-NEXT: dsll $2, $4, 1
; MIPS64R6-NEXT: sll $3, $7, 0
-; MIPS64R6-NEXT: not $5, $3
+; MIPS64R6-NEXT: xori $5, $3, 63
; MIPS64R6-NEXT: dsllv $2, $2, $5
; MIPS64R6-NEXT: or $1, $2, $1
; MIPS64R6-NEXT: andi $2, $3, 64
diff --git a/llvm/test/CodeGen/Mips/llvm-ir/shl.ll b/llvm/test/CodeGen/Mips/llvm-ir/shl.ll
index 77f9f0ed646ee2e..256da0b89e6038c 100644
--- a/llvm/test/CodeGen/Mips/llvm-ir/shl.ll
+++ b/llvm/test/CodeGen/Mips/llvm-ir/shl.ll
@@ -343,7 +343,7 @@ define signext i64 @shl_i64(i64 signext %a, i64 signext %b) {
; MIPS2-NEXT: nop
; MIPS2-NEXT: $BB4_3: # %entry
; MIPS2-NEXT: sllv $1, $4, $7
-; MIPS2-NEXT: not $2, $7
+; MIPS2-NEXT: xori $2, $7, 31
; MIPS2-NEXT: srl $3, $5, 1
; MIPS2-NEXT: srlv $2, $3, $2
; MIPS2-NEXT: or $2, $1, $2
@@ -356,7 +356,7 @@ define signext i64 @shl_i64(i64 signext %a, i64 signext %b) {
; MIPS32-LABEL: shl_i64:
; MIPS32: # %bb.0: # %entry
; MIPS32-NEXT: sllv $1, $4, $7
-; MIPS32-NEXT: not $2, $7
+; MIPS32-NEXT: xori $2, $7, 31
; MIPS32-NEXT: srl $3, $5, 1
; MIPS32-NEXT: srlv $2, $3, $2
; MIPS32-NEXT: or $2, $1, $2
@@ -369,7 +369,7 @@ define signext i64 @shl_i64(i64 signext %a, i64 signext %b) {
; MIPS32R2-LABEL: shl_i64:
; MIPS32R2: # %bb.0: # %entry
; MIPS32R2-NEXT: sllv $1, $4, $7
-; MIPS32R2-NEXT: not $2, $7
+; MIPS32R2-NEXT: xori $2, $7, 31
; MIPS32R2-NEXT: srl $3, $5, 1
; MIPS32R2-NEXT: srlv $2, $3, $2
; MIPS32R2-NEXT: or $2, $1, $2
@@ -382,7 +382,7 @@ define signext i64 @shl_i64(i64 signext %a, i64 signext %b) {
; MIPS32R6-LABEL: shl_i64:
; MIPS32R6: # %bb.0: # %entry
; MIPS32R6-NEXT: sllv $1, $4, $7
-; MIPS32R6-NEXT: not $2, $7
+; MIPS32R6-NEXT: xori $2, $7, 31
; MIPS32R6-NEXT: srl $3, $5, 1
; MIPS32R6-NEXT: srlv $2, $3, $2
; MIPS32R6-NEXT: or $1, $1, $2
@@ -422,9 +422,9 @@ define signext i64 @shl_i64(i64 signext %a, i64 signext %b) {
; MMR3-LABEL: shl_i64:
; MMR3: # %bb.0: # %entry
; MMR3-NEXT: sllv $3, $4, $7
-; MMR3-NEXT: not16 $2, $7
-; MMR3-NEXT: srl16 $4, $5, 1
-; MMR3-NEXT: srlv $2, $4, $2
+; MMR3-NEXT: xori $1, $7, 31
+; MMR3-NEXT: srl16 $2, $5, 1
+; MMR3-NEXT: srlv $2, $2, $1
; MMR3-NEXT: or16 $2, $3
; MMR3-NEXT: sllv $3, $5, $7
; MMR3-NEXT: andi16 $4, $7, 32
@@ -436,7 +436,7 @@ define signext i64 @shl_i64(i64 signext %a, i64 signext %b) {
; MMR6-LABEL: shl_i64:
; MMR6: # %bb.0: # %entry
; MMR6-NEXT: sllv $1, $4, $7
-; MMR6-NEXT: not16 $2, $7
+; MMR6-NEXT: xori $2, $7, 31
; MMR6-NEXT: srl16 $3, $5, 1
; MMR6-NEXT: srlv $2, $3, $2
; MMR6-NEXT: or $1, $1, $2
@@ -668,7 +668,7 @@ define signext i128 @shl_i128(i128 signext %a, i128 signext %b) {
; MIPS3-NEXT: .LBB5_3: # %entry
; MIPS3-NEXT: dsllv $1, $4, $7
; MIPS3-NEXT: dsrl $2, $5, 1
-; MIPS3-NEXT: not $3, $3
+; MIPS3-NEXT: xori $3, $3, 63
; MIPS3-NEXT: dsrlv $2, $2, $3
; MIPS3-NEXT: or $2, $1, $2
; MIPS3-NEXT: bnez $8, .LBB5_2
@@ -682,7 +682,7 @@ define signext i128 @shl_i128(i128 signext %a, i128 signext %b) {
; MIPS4-NEXT: dsllv $1, $4, $7
; MIPS4-NEXT: dsrl $2, $5, 1
; MIPS4-NEXT: sll $4, $7, 0
-; MIPS4-NEXT: not $3, $4
+; MIPS4-NEXT: xori $3, $4, 63
; MIPS4-NEXT: dsrlv $2, $2, $3
; MIPS4-NEXT: or $2, $1, $2
; MIPS4-NEXT: dsllv $3, $5, $7
@@ -696,7 +696,7 @@ define signext i128 @shl_i128(i128 signext %a, i128 signext %b) {
; MIPS64-NEXT: dsllv $1, $4, $7
; MIPS64-NEXT: dsrl $2, $5, 1
; MIPS64-NEXT: sll $4, $7, 0
-; MIPS64-NEXT: not $3, $4
+; MIPS64-NEXT: xori $3, $4, 63
; MIPS64-NEXT: dsrlv $2, $2, $3
; MIPS64-NEXT: or $2, $1, $2
; MIPS64-NEXT: dsllv $3, $5, $7
@@ -710,7 +710,7 @@ define signext i128 @shl_i128(i128 signext %a, i128 signext %b) {
; MIPS64R2-NEXT: dsllv $1, $4, $7
; MIPS64R2-NEXT: dsrl $2, $5, 1
; MIPS64R2-NEXT: sll $4, $7, 0
-; MIPS64R2-NEXT: not $3, $4
+; MIPS64R2-NEXT: xori $3, $4, 63
; MIPS64R2-NEXT: dsrlv $2, $2, $3
; MIPS64R2-NEXT: or $2, $1, $2
; MIPS64R2-NEXT: dsllv $3, $5, $7
@@ -724,7 +724,7 @@ define signext i128 @shl_i128(i128 signext %a, i128 signext %b) {
; MIPS64R6-NEXT: dsllv $1, $4, $7
; MIPS64R6-NEXT: dsrl $2, $5, 1
; MIPS64R6-NEXT: sll $3, $7, 0
-; MIPS64R6-NEXT: not $4, $3
+; MIPS64R6-NEXT: xori $4, $3, 63
; MIPS64R6-NEXT: dsrlv $2, $2, $4
; MIPS64R6-NEXT: or $1, $1, $2
; MIPS64R6-NEXT: andi $2, $3, 64
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