[llvm] 8775232 - [ValueTracking] Remove handling of KnownBits assumptions with invert
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 17 01:42:28 PST 2023
Author: Nikita Popov
Date: 2023-11-17T10:42:18+01:00
New Revision: 8775232c49cde288c429e27dd0f4f492fbb0cefa
URL: https://github.com/llvm/llvm-project/commit/8775232c49cde288c429e27dd0f4f492fbb0cefa
DIFF: https://github.com/llvm/llvm-project/commit/8775232c49cde288c429e27dd0f4f492fbb0cefa.diff
LOG: [ValueTracking] Remove handling of KnownBits assumptions with invert
For all practical purposes, we only care about comparisons with
constant RHS in this code. In that case, an invert will be
canonicalized into the constant and it will be handled by other cases.
Given the complete lack of test coverage, I'm removing this code.
Added:
Modified:
llvm/lib/Analysis/AssumptionCache.cpp
llvm/lib/Analysis/ValueTracking.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/AssumptionCache.cpp b/llvm/lib/Analysis/AssumptionCache.cpp
index bbcf25edf315b55..81b26678ae5d790 100644
--- a/llvm/lib/Analysis/AssumptionCache.cpp
+++ b/llvm/lib/Analysis/AssumptionCache.cpp
@@ -94,13 +94,7 @@ findAffectedValues(CallBase *CI, TargetTransformInfo *TTI,
if (Pred == ICmpInst::ICMP_EQ) {
// For equality comparisons, we handle the case of bit inversion.
auto AddAffectedFromEq = [&AddAffected](Value *V) {
- Value *A;
- if (match(V, m_Not(m_Value(A)))) {
- AddAffected(A);
- V = A;
- }
-
- Value *B;
+ Value *A, *B;
// (A & B) or (A | B) or (A ^ B).
if (match(V, m_BitwiseLogic(m_Value(A), m_Value(B)))) {
AddAffected(A);
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 5f5d7e07cac1e46..e25aa9c6863f335 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -662,16 +662,6 @@ static void computeKnownBitsFromCmp(const Value *V, const ICmpInst *Cmp,
// known bits from the RHS to V.
Known.Zero |= RHSKnown.Zero & MaskKnown.One;
Known.One |= RHSKnown.One & MaskKnown.One;
- // assume(~(v & b) = a)
- } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))),
- m_Value(A)))) {
- KnownBits RHSKnown = computeKnownBits(A, Depth + 1, QueryNoAC);
- KnownBits MaskKnown = computeKnownBits(B, Depth + 1, QueryNoAC);
-
- // For those bits in the mask that are known to be one, we can propagate
- // inverted known bits from the RHS to V.
- Known.Zero |= RHSKnown.One & MaskKnown.One;
- Known.One |= RHSKnown.Zero & MaskKnown.One;
// assume(v | b = a)
} else if (match(Cmp,
m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), m_Value(A)))) {
@@ -682,16 +672,6 @@ static void computeKnownBitsFromCmp(const Value *V, const ICmpInst *Cmp,
// bits from the RHS to V.
Known.Zero |= RHSKnown.Zero & BKnown.Zero;
Known.One |= RHSKnown.One & BKnown.Zero;
- // assume(~(v | b) = a)
- } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))),
- m_Value(A)))) {
- KnownBits RHSKnown = computeKnownBits(A, Depth + 1, QueryNoAC);
- KnownBits BKnown = computeKnownBits(B, Depth + 1, QueryNoAC);
-
- // For those bits in B that are known to be zero, we can propagate
- // inverted known bits from the RHS to V.
- Known.Zero |= RHSKnown.One & BKnown.Zero;
- Known.One |= RHSKnown.Zero & BKnown.Zero;
// assume(v ^ b = a)
} else if (match(Cmp,
m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), m_Value(A)))) {
@@ -705,19 +685,6 @@ static void computeKnownBitsFromCmp(const Value *V, const ICmpInst *Cmp,
Known.One |= RHSKnown.One & BKnown.Zero;
Known.Zero |= RHSKnown.One & BKnown.One;
Known.One |= RHSKnown.Zero & BKnown.One;
- // assume(~(v ^ b) = a)
- } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))),
- m_Value(A)))) {
- KnownBits RHSKnown = computeKnownBits(A, Depth + 1, QueryNoAC);
- KnownBits BKnown = computeKnownBits(B, Depth + 1, QueryNoAC);
-
- // For those bits in B that are known to be zero, we can propagate
- // inverted known bits from the RHS to V. For those bits in B that are
- // known to be one, we can propagate known bits from the RHS to V.
- Known.Zero |= RHSKnown.One & BKnown.Zero;
- Known.One |= RHSKnown.Zero & BKnown.Zero;
- Known.Zero |= RHSKnown.Zero & BKnown.One;
- Known.One |= RHSKnown.One & BKnown.One;
// assume(v << c = a)
} else if (match(Cmp, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)),
m_Value(A))) &&
@@ -729,17 +696,6 @@ static void computeKnownBitsFromCmp(const Value *V, const ICmpInst *Cmp,
RHSKnown.Zero.lshrInPlace(C);
RHSKnown.One.lshrInPlace(C);
Known = Known.unionWith(RHSKnown);
- // assume(~(v << c) = a)
- } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))),
- m_Value(A))) &&
- C < BitWidth) {
- KnownBits RHSKnown = computeKnownBits(A, Depth + 1, QueryNoAC);
- // For those bits in RHS that are known, we can propagate them inverted
- // to known bits in V shifted to the right by C.
- RHSKnown.One.lshrInPlace(C);
- Known.Zero |= RHSKnown.One;
- RHSKnown.Zero.lshrInPlace(C);
- Known.One |= RHSKnown.Zero;
// assume(v >> c = a)
} else if (match(Cmp, m_c_ICmp(Pred, m_Shr(m_V, m_ConstantInt(C)),
m_Value(A))) &&
@@ -749,15 +705,6 @@ static void computeKnownBitsFromCmp(const Value *V, const ICmpInst *Cmp,
// bits in V shifted to the right by C.
Known.Zero |= RHSKnown.Zero << C;
Known.One |= RHSKnown.One << C;
- // assume(~(v >> c) = a)
- } else if (match(Cmp, m_c_ICmp(Pred, m_Not(m_Shr(m_V, m_ConstantInt(C))),
- m_Value(A))) &&
- C < BitWidth) {
- KnownBits RHSKnown = computeKnownBits(A, Depth + 1, QueryNoAC);
- // For those bits in RHS that are known, we can propagate them inverted
- // to known bits in V shifted to the right by C.
- Known.Zero |= RHSKnown.One << C;
- Known.One |= RHSKnown.Zero << C;
}
break;
case ICmpInst::ICMP_NE: {
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