[llvm] [RISCV][llvm-mca] Vector Unit Stride Loads and stores use EEW and EMU… (PR #69409)

[Wang Pengcheng via llvm-commits]

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@@ -185,6 +187,59 @@ RISCVInstrumentManager::createInstruments(const MCInst &Inst) {
   return SmallVector<UniqueInstrument>();
 }
 
+/// Return EMUL = (EEW / SEW) * LMUL
+inline static std::pair<unsigned, bool>
+getEMULEqualsEEWDivSEWTimesLMUL(unsigned EEW, unsigned SEW,
+                                RISCVII::VLMUL VLMUL) {
+  // Calculate (EEW/SEW)*LMUL preserving fractions less than 1. Use GCD
+  // to put fraction in simplest form.
+  auto [LMUL, Fractional] = RISCVVType::decodeVLMUL(VLMUL);
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wangpc-pp wrote:

Why is fixed point approach not working? I tried it, it can calculate the right EMUL, see #69570.

https://github.com/llvm/llvm-project/pull/69409