[llvm] [X86] Try Folding icmp of v8i32 -> fcmp of v8f32 on AVX (PR #82290)
Simon Pilgrim via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 29 14:30:22 PST 2024
================
@@ -23296,6 +23303,136 @@ static SDValue LowerVSETCC(SDValue Op, const X86Subtarget &Subtarget,
}
}
+ // We get bad codegen for v8i32 compares on avx targets (without avx2) so if
+ // possible convert to a v8f32 compare.
+ if (VTOp0 == MVT::v8i32 && Subtarget.hasAVX() && !Subtarget.hasAVX2()) {
+ std::optional<KnownBits> KnownOps[2];
+ // Check if an op is known to be in a certain range.
+ auto OpInRange = [&DAG, Op, &KnownOps](unsigned OpNo, bool CmpLT,
+ const APInt Bound) {
+ if (!KnownOps[OpNo].has_value())
+ KnownOps[OpNo] = DAG.computeKnownBits(Op.getOperand(OpNo));
+
+ if (KnownOps[OpNo]->isUnknown())
+ return false;
+
+ std::optional<bool> Res;
+ if (CmpLT)
+ Res = KnownBits::ult(*KnownOps[OpNo], KnownBits::makeConstant(Bound));
+ else
+ Res = KnownBits::ugt(*KnownOps[OpNo], KnownBits::makeConstant(Bound));
+ return Res.has_value() && *Res;
+ };
+
+ bool OkayCvt = false;
+ bool OkayBitcast = false;
+
+ const fltSemantics &Sem = SelectionDAG::EVTToAPFloatSemantics(MVT::f32);
+
+ // For cvt up to 1 << (Significand Precision), (1 << 24 for ieee float)
+ const APInt MaxConvertableCvt =
+ APInt(32, (1U << APFloat::semanticsPrecision(Sem)));
----------------
RKSimon wrote:
APint::getOneBitSet(32, APFloat::semanticsPrecision(Sem))
https://github.com/llvm/llvm-project/pull/82290
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