[llvm] [X86][AVX512] Use comx for compare (PR #113098)
Phoebe Wang via llvm-commits
llvm-commits at lists.llvm.org
Sun Oct 20 17:20:37 PDT 2024
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@@ -49520,6 +49520,15 @@ static SDValue combineCompareEqual(SDNode *N, SelectionDAG &DAG,
// FIXME: need symbolic constants for these magic numbers.
// See X86ATTInstPrinter.cpp:printSSECC().
unsigned x86cc = (cc0 == X86::COND_E) ? 0 : 4;
+
+ // VCOMXSS simplifies conditional code sequence into single setcc node.
+ // Earlier until COMI, it required upto 2 SETCC's to test CC.
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phoebewang wrote:
I don't understand the logic here. Why do we require 2 CC for comx? I don't see a test case using 2 CC. Can we just return `SDValue()` to break combine?
https://github.com/llvm/llvm-project/pull/113098
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