Fix `vacc` destination widening

PiperOrigin-RevId: 561722481

sim/kelvin_encoding.cc

diff --git a/sim/kelvin_encoding.cc b/sim/kelvin_encoding.cc
index f085f59..5b68af7 100644
--- a/sim/kelvin_encoding.cc
+++ b/sim/kelvin_encoding.cc
@@ -384,6 +384,11 @@
     return true;
   }
 
+  // Func1 0b100 VAcc.[h,w].[u] needs 2x destination registers.
+  if ((func1 == 0b100) && (func2_ignore_unsigned == 0b1010)) {
+    return true;
+  }
+
   // Func1 0b001 VMvp also needs 2x destination registers.
   if ((func1 == 0b001) && (func2 == 0b1101)) {
     return true;

sim/test/kelvin_encoding_test.cc

diff --git a/sim/test/kelvin_encoding_test.cc b/sim/test/kelvin_encoding_test.cc
index f790aa1..8dad336 100644
--- a/sim/test/kelvin_encoding_test.cc
+++ b/sim/test/kelvin_encoding_test.cc
@@ -97,6 +97,7 @@
 constexpr uint32_t kVld = 0b000000'000000'000000'00'000000'0'111'11;
 
 // Kelvin vector ops
+constexpr uint32_t kVAccsBase = 0b001010'000001'000000'00'001000'0'100'00;
 constexpr uint32_t kVAddBase = 0b000000'000000'000001'00'000010'0'000'00;
 constexpr uint32_t kAconvBase = 0b001000'000001'010000'10'110000'0'00'101;
 
@@ -443,7 +444,6 @@
   EXPECT_EQ(enc_->GetOpcode(SlotEnum::kKelvin, 0), OpcodeEnum::kNone);
 
   // Test vacc.h.vv
-  constexpr uint32_t kVAccsBase = 0b001010'000001'000000'00'001000'0'100'00;
   v_src = EncodeOpHelper<RV32VectorSourceOperand>(
       SetSz(kVAccsBase, 0b1), OpcodeEnum::kVaccHVv, SourceOpEnum::kVs1);
   EXPECT_EQ(v_src->size(), 2);
@@ -509,6 +509,25 @@
   EXPECT_EQ(v_dest->size(), 2);
   delete v_dest;
 
+  // Test vacc.h.vv
+  v_dest = EncodeOpHelper<RV32VectorDestOperand>(
+      SetSz(kVAccsBase, 0b1), OpcodeEnum::kVaccHVv, DestOpEnum::kVd);
+  EXPECT_EQ(v_dest->size(), 2);
+  delete v_dest;
+
+  // Test vacc.w.u.vv
+  v_dest = EncodeOpHelper<RV32VectorDestOperand>(
+      SetSz(kVAccsBase, 0b10) | (1 << 26), OpcodeEnum::kVaccWUVv,
+      DestOpEnum::kVd);
+  EXPECT_EQ(v_dest->size(), 2);
+  delete v_dest;
+
+  // Test no-widening of vle(same func2 as vacc, func1 == 000)
+  v_dest = EncodeOpHelper<RV32VectorDestOperand>(
+      kVAccsBase & ~(1 << 4), OpcodeEnum::kVleBVv, DestOpEnum::kVd);
+  EXPECT_EQ(v_dest->size(), 1);
+  delete v_dest;
+
   // Test vmvp.vv
   constexpr uint32_t kVMvpBase = 0b001101'000001'000000'00'001000'0'001'00;
   v_dest = EncodeOpHelper<RV32VectorDestOperand>(kVMvpBase, OpcodeEnum::kVmvpVv,