RISCV: Remove faulty assert that ignored subregister uses #141658
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This was asserting the raw virtual register class was a scalar class, instead of computing the net result of the register class plus the subregister index on the operand. The machine verifier should be checking this was a valid combination in the first place, so just drop the assert.
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@llvm/pr-subscribers-backend-risc-v Author: Matt Arsenault (arsenm) ChangesThis was asserting the raw virtual register class was a scalar Full diff: https://github.com/llvm/llvm-project/pull/141658.diff 2 Files Affected:
diff --git a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
index f7cbfa1546de6..0bb81a58c29a4 100644
--- a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
@@ -1298,12 +1298,7 @@ RISCVVLOptimizer::getMinimumVLForUser(const MachineOperand &UserOp) const {
// Instructions like reductions may use a vector register as a scalar
// register. In this case, we should treat it as only reading the first lane.
if (isVectorOpUsedAsScalarOp(UserOp)) {
- [[maybe_unused]] Register R = UserOp.getReg();
- [[maybe_unused]] const TargetRegisterClass *RC = MRI->getRegClass(R);
- assert(RISCV::VRRegClass.hasSubClassEq(RC) &&
- "Expect LMUL 1 register class for vector as scalar operands!");
LLVM_DEBUG(dbgs() << " Used this operand as a scalar operand\n");
-
return MachineOperand::CreateImm(1);
}
diff --git a/llvm/test/CodeGen/RISCV/rvv/vl-optimizer-subreg-assert.mir b/llvm/test/CodeGen/RISCV/rvv/vl-optimizer-subreg-assert.mir
new file mode 100644
index 0000000000000..b816741285b43
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/rvv/vl-optimizer-subreg-assert.mir
@@ -0,0 +1,32 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=riscv64 -mattr=+v -run-pass=riscv-vl-optimizer -o - %s | FileCheck %s
+# Check that there is no assert on subregister uses.
+
+---
+name: vl_optimizer_subreg_assert
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $v8m2
+
+ ; CHECK-LABEL: name: vl_optimizer_subreg_assert
+ ; CHECK: liveins: $v8m2
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[DEF:%[0-9]+]]:vrm8 = IMPLICIT_DEF
+ ; CHECK-NEXT: [[DEF1:%[0-9]+]]:vmv0 = IMPLICIT_DEF
+ ; CHECK-NEXT: [[DEF2:%[0-9]+]]:vrm8 = IMPLICIT_DEF
+ ; CHECK-NEXT: [[PseudoVMERGE_VVM_M8_:%[0-9]+]]:vrm8nov0 = PseudoVMERGE_VVM_M8 $noreg, killed [[DEF2]], [[DEF]], [[DEF1]], -1, 6 /* e64 */
+ ; CHECK-NEXT: [[PseudoVREDMAXU_VS_M8_E64_:%[0-9]+]]:vr = PseudoVREDMAXU_VS_M8_E64 $noreg, [[PseudoVMERGE_VVM_M8_]], [[PseudoVMERGE_VVM_M8_]].sub_vrm1_0, -1, 6 /* e64 */, 1 /* ta, mu */
+ ; CHECK-NEXT: [[PseudoVMV_X_S:%[0-9]+]]:gpr = PseudoVMV_X_S killed [[PseudoVREDMAXU_VS_M8_E64_]], 6 /* e64 */
+ ; CHECK-NEXT: $x10 = COPY [[PseudoVMV_X_S]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:vrm8 = IMPLICIT_DEF
+ %1:vmv0 = IMPLICIT_DEF
+ %2:vrm8 = IMPLICIT_DEF
+ %3:vrm8nov0 = PseudoVMERGE_VVM_M8 $noreg, killed %2, %0, %1, -1, 6 /* e64 */
+ %4:vr = PseudoVREDMAXU_VS_M8_E64 $noreg, %3, %3.sub_vrm1_0, -1, 6 /* e64 */, 1 /* ta, mu */
+ %5:gpr = PseudoVMV_X_S killed %4, 6 /* e64 */
+ $x10 = COPY %5
+ PseudoRET implicit $x10
+
+...
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/137/builds/19310 Here is the relevant piece of the build log for the reference |
sivan-shani
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Jun 3, 2025
This was asserting the raw virtual register class was a scalar class, instead of computing the net result of the register class plus the subregister index on the operand. The machine verifier should be checking this was a valid combination in the first place, so just drop the assert.
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This was asserting the raw virtual register class was a scalar
class, instead of computing the net result of the register class
plus the subregister index on the operand. The machine verifier
should be checking this was a valid combination in the first place,
so just drop the assert.