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arm64: Fix negs compare to minus int.MinValue #121380

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Merged
jakobbotsch merged 7 commits into from
Dec 4, 2025
Merged

arm64: Fix negs compare to minus int.MinValue #121380

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972b88a
arm64: Fix negs compare to minus int.MinValue
jonathandavies-arm Nov 5, 2025
0208da9
Remove SupportsSettingResultFlags()
jonathandavies-arm Nov 7, 2025
9587885
Merge branch 'main' into upstream/issue/121294
jonathandavies-arm Nov 10, 2025
40ea320
Merge branch 'main' into upstream/issue/121294
jonathandavies-arm Nov 14, 2025
7661629
Add SupportsSettingFlagsAsCompareToZero
jonathandavies-arm Nov 18, 2025
a664e3c
Move checks into SupportsSettingFlagsAsCompareToZero
jakobbotsch Nov 25, 2025
566c9de
Run jit-format
jakobbotsch Nov 25, 2025
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4 changes: 2 additions & 2 deletions src/coreclr/jit/lower.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4435,10 +4435,10 @@ GenTree* Lowering::OptimizeConstCompare(GenTree* cmp)
}

// Optimize EQ/NE/GT/GE/LT/LE(op_that_sets_zf, 0) into op_that_sets_zf with GTF_SET_FLAGS + SETCC.
// For GT/GE/LT/LE don't allow ADD/SUB, runtime has to check for overflow.
// For GT/GE/LT/LE don't allow ADD/SUB/NEG, runtime has to check for overflow.
LIR::Use use;
if (((cmp->OperIs(GT_EQ, GT_NE) && op2->IsIntegralConst(0) && op1->SupportsSettingZeroFlag()) ||
(cmp->OperIs(GT_GT, GT_GE, GT_LT, GT_LE) && op2->IsIntegralConst(0) && !op1->OperIs(GT_ADD, GT_SUB) &&
(cmp->OperIs(GT_GT, GT_GE, GT_LT, GT_LE) && op2->IsIntegralConst(0) && !op1->OperIs(GT_ADD, GT_SUB, GT_NEG) &&
op1->SupportsSettingResultFlags())) &&
BlockRange().TryGetUse(cmp, &use) && IsProfitableToSetZeroFlag(op1))
{
Expand Down
52 changes: 47 additions & 5 deletions src/tests/JIT/opt/InstructionCombining/Neg.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -115,6 +115,16 @@ public static int CheckNeg()
fail = true;
}

if (NegsGreaterThanIntMinValue())
{
fail = true;
}

if (NegsGreaterThanLongMinValue())
{
fail = true;
}

if (fail)
{
return 101;
Expand Down Expand Up @@ -266,33 +276,65 @@ static bool NegsBinOpSingleLine(int a, int b)
//ARM64-FULL-LINE: negs {{w[0-9]+}}, {{w[0-9]+}}, LSL #1
return (-(a >> 1) != 0) | (-(b << 1) != 0);
}

[MethodImpl(MethodImplOptions.NoInlining)]
static bool NegsGreaterThan(int a)
{
//ARM64-FULL-LINE: negs {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: neg {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: cmp {{w[0-9]+}}, #0
return -a > 0;
}

[MethodImpl(MethodImplOptions.NoInlining)]
static bool NegsGreaterThanEq(int a)
{
//ARM64-FULL-LINE: negs {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: neg {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: cmp {{w[0-9]+}}, #0
return -a >= 0;
}

[MethodImpl(MethodImplOptions.NoInlining)]
static bool NegsLessThan(int a)
{
//ARM64-FULL-LINE: negs {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: neg {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: lsr {{w[0-9]+}}, {{w[0-9]+}}, #31
return -a < 0;
}

[MethodImpl(MethodImplOptions.NoInlining)]
static bool NegsLessThanEq(int a)
{
//ARM64-FULL-LINE: negs {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: neg {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: cmp {{w[0-9]+}}, #0
return -a <= 0;
}

[MethodImpl(MethodImplOptions.NoInlining)]
static bool NegsGreaterThanIntMinValue()
{
//ARM64-FULL-LINE: neg {{w[0-9]+}}, {{w[0-9]+}}
//ARM64-FULL-LINE: cmp {{w[0-9]+}}, #0
return -IntMinValue() > 0;
}

[MethodImpl(MethodImplOptions.NoInlining)]
static bool NegsGreaterThanLongMinValue()
{
//ARM64-FULL-LINE: neg {{x[0-9]+}}, {{x[0-9]+}}
//ARM64-FULL-LINE: cmp {{x[0-9]+}}, #0
return -LongMinValue() > 0;
}

[MethodImpl(MethodImplOptions.NoInlining)]
static int IntMinValue()
{
return int.MinValue;
}

[MethodImpl(MethodImplOptions.NoInlining)]
static long LongMinValue()
{
return long.MinValue;
}
}
}
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