[RISCV] Rewrite CheckInvalidVLENandLMUL to avoid floating point.

This avoids needing an FP value to represent LMUL.

Reviewed By: 4vtomat

Differential Revision: https://reviews.llvm.org/D157651

1 files changed, 18 insertions, 8 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index dc45e8d..8c3abc2 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -4474,14 +4474,24 @@ static bool CheckInvalidVLENandLMUL(const TargetInfo &TI, CallExpr *TheCall,
   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 :
-                       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 ElemSize = Type->isRVVType(32, false) ? 32 : 64;
+  unsigned MinElemCount = Type->isRVVType(1)   ? 1
+                          : Type->isRVVType(2) ? 2
+                          : Type->isRVVType(4) ? 4
+                          : Type->isRVVType(8) ? 8
+                                               : 16;
+
+  unsigned EGS = EGW / ElemSize;
+  // If EGS is less than or equal to the minimum number of elements, then the
+  // type is valid.
+  if (EGS <= MinElemCount)
+    return false;
+
+  // Otherwise, we need vscale to be at least EGS / MinElemCont.
+  assert(EGS % MinElemCount == 0);
+  unsigned VScaleFactor = EGS / MinElemCount;
+  // 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(),