[PATCH] D157651: [RISCV] Rewrite CheckInvalidVLENandLMUL to avoid floating point.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: 4vtomat, kito-cheng, reames, asb.
Herald added subscribers: jobnoorman, VincentWu, vkmr, luismarques, sameer.abuasal, s.egerton, Jim, benna, psnobl, rogfer01, shiva0217, simoncook, arichardson.
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craig.topper requested review of this revision.
Herald added subscribers: cfe-commits, wangpc, eopXD.
Herald added a project: clang.

This avoids needing an FP value to represent LMUL.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D157651

Files:
  clang/lib/Sema/SemaChecking.cpp


Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -4473,14 +4473,22 @@
   assert((EGW == 128 || EGW == 256) && "EGW can only be 128 or 256 bits");
 
   // LMUL * VLEN >= EGW
-  uint64_t ElemSize = Type->isRVVType(32, false) ? 32 : 64;
-  uint64_t ElemCount = Type->isRVVType(1) ? 1 :
+  unsigned ElemSize = Type->isRVVType(32, false) ? 32 : 64;
+  unsigned ElemCount = Type->isRVVType(1) ? 1 :
                        Type->isRVVType(2) ? 2 :
                        Type->isRVVType(4) ? 4 :
                        Type->isRVVType(8) ? 8 :
                        16;
-  float Lmul = (float)(ElemSize * ElemCount) / llvm::RISCV::RVVBitsPerBlock;
-  uint64_t MinRequiredVLEN = std::max(EGW / Lmul, (float)ElemSize);
+
+  unsigned EGS = EGW / ElemSize;
+  // If EGS is more than our minimum number of elements we're done.
+  if (EGS <= ElemCount)
+    return false;
+
+  // We need vscale to be at least this value.
+  unsigned VScaleFactor = EGS / ElemCount;
+  // Vscale is VLEN/RVVBitsPerBlock.
+  unsigned MinRequiredVLEN = VScaleFactor * llvm::RISCV::RVVBitsPerBlock;
   std::string RequiredExt = "zvl" + std::to_string(MinRequiredVLEN) + "b";
   if (!TI.hasFeature(RequiredExt))
     return S.Diag(TheCall->getBeginLoc(),


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