fixup! improve tests, move check to isCandidate

Author: michaelmaitland

llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp

@@ -961,8 +961,6 @@ static bool isSupportedInstr(const MachineInstr &MI) {
   case RISCV::VMSOF_M:
   case RISCV::VIOTA_M:
   case RISCV::VID_V:
-    return true;
-
   // Single-Width Floating-Point/Integer Type-Convert Instructions
   case RISCV::VFCVT_XU_F_V:
   case RISCV::VFCVT_X_F_V:
@@ -987,7 +985,8 @@ static bool isSupportedInstr(const MachineInstr &MI) {
   case RISCV::VFNCVT_F_X_W:
   case RISCV::VFNCVT_F_F_W:
   case RISCV::VFNCVT_ROD_F_F_W:
-    return MI.getFlags() & MachineInstr::NoFPExcept;
+    return true;
+
   }
 
   return false;
@@ -1093,6 +1092,11 @@ bool RISCVVLOptimizer::isCandidate(const MachineInstr &MI) const {
     return false;
   }
 
+  if (MI.mayRaiseFPException()) {
+    LLVM_DEBUG(dbgs() << "Not a candidate because may raise FP exception\n");
+    return false;
+  }
+
   // Some instructions that produce vectors have semantics that make it more
   // difficult to determine whether the VL can be reduced. For example, some
   // instructions, such as reductions, may write lanes past VL to a scalar

llvm/test/CodeGen/RISCV/rvv/vl-opt.mir

@@ -111,16 +111,23 @@ body: |
     %z:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, -1, 3 /* e8 */, 0
 ...
 ---
-name: vfcvt.x.f.v
+name: vfcvt_x_f_v_nofpexcept
 body: |
   bb.0:
-    liveins: $x1
-    ; CHECK-LABEL: name: vfcvt.x.f.v
-    ; CHECK: liveins: $x1
-    ; CHECK-NEXT: {{  $}}
-    ; CHECK-NEXT: %x:vr = nofpexcept PseudoVFCVT_X_F_V_M1 $noreg, $noreg, 0, 1, 3 /* e8 */, 0 /* tu, mu */
+    ; CHECK-LABEL: name: vfcvt_x_f_v_nofpexcept
+    ; CHECK: %x:vr = nofpexcept PseudoVFCVT_X_F_V_M1 $noreg, $noreg, 0, 1, 3 /* e8 */, 0 /* tu, mu */
     ; CHECK-NEXT: %y:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, 1, 3 /* e8 */, 0 /* tu, mu */
     %x:vr = nofpexcept PseudoVFCVT_X_F_V_M1 $noreg, $noreg, 0, -1, 3 /* e32 */, 0
     %y:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, 1, 3 /* e8 */, 0
 ...
+---
+name: vfcvt_x_f_v_fpexcept
+body: |
+  bb.0:
+    ; CHECK-LABEL: name: vfcvt_x_f_v_fpexcept
+    ; CHECK: %x:vr = PseudoVFCVT_X_F_V_M1 $noreg, $noreg, 0, -1, 3 /* e8 */, 0 /* tu, mu */
+    ; CHECK-NEXT: %y:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, 1, 3 /* e8 */, 0 /* tu, mu */
+    %x:vr = PseudoVFCVT_X_F_V_M1 $noreg, $noreg, 0, -1, 3 /* e32 */, 0
+    %y:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, 1, 3 /* e8 */, 0
+...