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Backport "eq of parts" fold with logical ops #113

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Aug 26, 2021
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Backport "eq of parts" fold with logical ops #113

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5ed5b4e
[InstCombine] Add tests for "eq of parts" with logical op (NFC)
nikic Aug 22, 2021
a9f1947
[InstCombine] Perform "eq of parts" fold with logical ops
nikic Aug 22, 2021
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8 changes: 4 additions & 4 deletions llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1113,8 +1113,8 @@ static Value *extractIntPart(const IntPart &P, IRBuilderBase &Builder) {
/// (icmp eq X0, Y0) & (icmp eq X1, Y1) -> icmp eq X01, Y01
/// (icmp ne X0, Y0) | (icmp ne X1, Y1) -> icmp ne X01, Y01
/// where X0, X1 and Y0, Y1 are adjacent parts extracted from an integer.
static Value *foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1, bool IsAnd,
InstCombiner::BuilderTy &Builder) {
Value *InstCombinerImpl::foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool IsAnd) {
if (!Cmp0->hasOneUse() || !Cmp1->hasOneUse())
return nullptr;

Expand Down Expand Up @@ -1262,7 +1262,7 @@ Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
foldUnsignedUnderflowCheck(RHS, LHS, /*IsAnd=*/true, Q, Builder))
return X;

if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/true, Builder))
if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/true))
return X;

// This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
Expand Down Expand Up @@ -2496,7 +2496,7 @@ Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
foldUnsignedUnderflowCheck(RHS, LHS, /*IsAnd=*/false, Q, Builder))
return X;

if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/false, Builder))
if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/false))
return X;

// (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
Expand Down
2 changes: 2 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineInternal.h
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Expand Up @@ -347,6 +347,8 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
Value *foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, BinaryOperator &Or);
Value *foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS, BinaryOperator &Xor);

Value *foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1, bool IsAnd);

/// Optimize (fcmp)&(fcmp) or (fcmp)|(fcmp).
/// NOTE: Unlike most of instcombine, this returns a Value which should
/// already be inserted into the function.
Expand Down
9 changes: 7 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Expand Up @@ -2754,11 +2754,16 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
/* IsAnd */ IsAnd))
return I;

if (auto *ICmp0 = dyn_cast<ICmpInst>(CondVal))
if (auto *ICmp1 = dyn_cast<ICmpInst>(Op1))
if (auto *ICmp0 = dyn_cast<ICmpInst>(CondVal)) {
if (auto *ICmp1 = dyn_cast<ICmpInst>(Op1)) {
if (auto *V = foldAndOrOfICmpsOfAndWithPow2(ICmp0, ICmp1, &SI, IsAnd,
/* IsLogical */ true))
return replaceInstUsesWith(SI, V);

if (auto *V = foldEqOfParts(ICmp0, ICmp1, IsAnd))
return replaceInstUsesWith(SI, V);
}
}
}

// select (select a, true, b), c, false -> select a, c, false
Expand Down
50 changes: 50 additions & 0 deletions llvm/test/Transforms/InstCombine/eq-of-parts.ll
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Expand Up @@ -352,6 +352,31 @@ define i1 @eq_21_extra_use_eq2(i32 %x, i32 %y) {
ret i1 %c.210
}

; Logical and instead of bitwise and.

define i1 @eq_21_logical(i32 %x, i32 %y) {
; CHECK-LABEL: @eq_21_logical(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 [[X:%.*]], 8
; CHECK-NEXT: [[TMP2:%.*]] = trunc i32 [[TMP1]] to i16
; CHECK-NEXT: [[TMP3:%.*]] = lshr i32 [[Y:%.*]], 8
; CHECK-NEXT: [[TMP4:%.*]] = trunc i32 [[TMP3]] to i16
; CHECK-NEXT: [[TMP5:%.*]] = icmp eq i16 [[TMP2]], [[TMP4]]
; CHECK-NEXT: ret i1 [[TMP5]]
;
%x.321 = lshr i32 %x, 8
%x.1 = trunc i32 %x.321 to i8
%x.32 = lshr i32 %x, 16
%x.2 = trunc i32 %x.32 to i8
%y.321 = lshr i32 %y, 8
%y.1 = trunc i32 %y.321 to i8
%y.32 = lshr i32 %y, 16
%y.2 = trunc i32 %y.32 to i8
%c.1 = icmp eq i8 %x.1, %y.1
%c.2 = icmp eq i8 %x.2, %y.2
%c.210 = select i1 %c.2, i1 %c.1, i1 false
ret i1 %c.210
}

; Negative tests.

define i1 @eq_21_wrong_op1(i32 %x, i32 %y, i32 %z) {
Expand Down Expand Up @@ -992,6 +1017,31 @@ define i1 @ne_21_extra_use_ne2(i32 %x, i32 %y) {
ret i1 %c.210
}

; Logical or instead of bitwise or.

define i1 @ne_21_logical(i32 %x, i32 %y) {
; CHECK-LABEL: @ne_21_logical(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 [[X:%.*]], 8
; CHECK-NEXT: [[TMP2:%.*]] = trunc i32 [[TMP1]] to i16
; CHECK-NEXT: [[TMP3:%.*]] = lshr i32 [[Y:%.*]], 8
; CHECK-NEXT: [[TMP4:%.*]] = trunc i32 [[TMP3]] to i16
; CHECK-NEXT: [[TMP5:%.*]] = icmp ne i16 [[TMP2]], [[TMP4]]
; CHECK-NEXT: ret i1 [[TMP5]]
;
%x.321 = lshr i32 %x, 8
%x.1 = trunc i32 %x.321 to i8
%x.32 = lshr i32 %x, 16
%x.2 = trunc i32 %x.32 to i8
%y.321 = lshr i32 %y, 8
%y.1 = trunc i32 %y.321 to i8
%y.32 = lshr i32 %y, 16
%y.2 = trunc i32 %y.32 to i8
%c.1 = icmp ne i8 %x.1, %y.1
%c.2 = icmp ne i8 %x.2, %y.2
%c.210 = select i1 %c.2, i1 true, i1 %c.1
ret i1 %c.210
}

; Negative tests.

define i1 @ne_21_wrong_op1(i32 %x, i32 %y, i32 %z) {
Expand Down