diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index ed857ddbc78..baf72a0bf37 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -3908,27 +3908,44 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, Pred == ICmpInst::ICMP_EQ)) return V; - // Test for zero-shift-guard-ops around funnel shifts. These are used to - // avoid UB from oversized shifts in raw IR rotate patterns, but the - // intrinsics do not have that problem. + // Test for a bogus zero-shift-guard-op around funnel-shift or rotate. Value *ShAmt; auto isFsh = m_CombineOr(m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), m_Value(ShAmt)), m_Intrinsic<Intrinsic::fshr>(m_Value(), m_Value(X), m_Value(ShAmt))); - // (ShAmt != 0) ? fshl(X, *, ShAmt) : X --> fshl(X, *, ShAmt) - // (ShAmt != 0) ? fshr(*, X, ShAmt) : X --> fshr(*, X, ShAmt) // (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X // (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X - if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt) - return Pred == ICmpInst::ICMP_NE ? TrueVal : X; - - // (ShAmt == 0) ? X : fshl(X, *, ShAmt) --> fshl(X, *, ShAmt) - // (ShAmt == 0) ? X : fshr(*, X, ShAmt) --> fshr(*, X, ShAmt) + if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt && + Pred == ICmpInst::ICMP_EQ) + return X; // (ShAmt != 0) ? X : fshl(X, *, ShAmt) --> X // (ShAmt != 0) ? X : fshr(*, X, ShAmt) --> X - if (match(FalseVal, isFsh) && TrueVal == X && CmpLHS == ShAmt) - return Pred == ICmpInst::ICMP_EQ ? FalseVal : X; + if (match(FalseVal, isFsh) && TrueVal == X && CmpLHS == ShAmt && + Pred == ICmpInst::ICMP_NE) + return X; + + // Test for a zero-shift-guard-op around rotates. These are used to + // avoid UB from oversized shifts in raw IR rotate patterns, but the + // intrinsics do not have that problem. + // We do not allow this transform for the general funnel shift case because + // that would not preserve the poison safety of the original code. + auto isRotate = m_CombineOr(m_Intrinsic<Intrinsic::fshl>(m_Value(X), + m_Deferred(X), + m_Value(ShAmt)), + m_Intrinsic<Intrinsic::fshr>(m_Value(X), + m_Deferred(X), + m_Value(ShAmt))); + // (ShAmt != 0) ? fshl(X, X, ShAmt) : X --> fshl(X, X, ShAmt) + // (ShAmt != 0) ? fshr(X, X, ShAmt) : X --> fshr(X, X, ShAmt) + if (match(TrueVal, isRotate) && FalseVal == X && CmpLHS == ShAmt && + Pred == ICmpInst::ICMP_NE) + return TrueVal; + // (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt) + // (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt) + if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt && + Pred == ICmpInst::ICMP_EQ) + return FalseVal; } // Check for other compares that behave like bit test. |
