[RISCV] Remove -riscv-insert-vsetvl-strict-asserts flag

[lukel97]

This flag has been enabled by default for almost two years now since 1f06398, and at this stage we probably shouldn't be falling back to the fixups.

This removes the flag so we always perform the assertion, as well as making sure that CurInfo is always valid on exit: We shouldn't leave emitVSETVLIs with an uninitialized VSETVLIInfo.

[llvmbot]

@llvm/pr-subscribers-backend-risc-v

Author: Luke Lau (lukel97)

Changes

This flag has been enabled by default for almost two years now since 1f06398, and at this stage we probably shouldn't be falling back to the fixups.

This removes the flag so we always perform the assertion, as well as making sure that CurInfo is always valid on exit: We shouldn't leave emitVSETVLIs with an unitialized VSETVLIInfo.

---

Full diff: https://github.com/llvm/llvm-project/pull/90171.diff

1 Files Affected:

• (modified) llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp (+8-29)

diff --git a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
index c40b9031543fe2..90fa0920c49283 100644
--- a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
@@ -45,10 +45,6 @@ static cl::opt<bool> DisableInsertVSETVLPHIOpt(
     "riscv-disable-insert-vsetvl-phi-opt", cl::init(false), cl::Hidden,
     cl::desc("Disable looking through phis when inserting vsetvlis."));
 
-static cl::opt<bool> UseStrictAsserts(
-    "riscv-insert-vsetvl-strict-asserts", cl::init(true), cl::Hidden,
-    cl::desc("Enable strict assertion checking for the dataflow algorithm"));
-
 namespace {
 
 static unsigned getVLOpNum(const MachineInstr &MI) {
@@ -1430,32 +1426,15 @@ void RISCVInsertVSETVLI::emitVSETVLIs(MachineBasicBlock &MBB) {
     transferAfter(CurInfo, MI);
   }
 
-  // If we reach the end of the block and our current info doesn't match the
-  // expected info, insert a vsetvli to correct.
-  if (!UseStrictAsserts) {
-    const VSETVLIInfo &ExitInfo = BlockInfo[MBB.getNumber()].Exit;
-    if (CurInfo.isValid() && ExitInfo.isValid() && !ExitInfo.isUnknown() &&
-        CurInfo != ExitInfo) {
-      // Note there's an implicit assumption here that terminators never use
-      // or modify VL or VTYPE.  Also, fallthrough will return end().
-      auto InsertPt = MBB.getFirstInstrTerminator();
-      insertVSETVLI(MBB, InsertPt, MBB.findDebugLoc(InsertPt), ExitInfo,
-                    CurInfo);
-      CurInfo = ExitInfo;
-    }
-  }
-
-  if (UseStrictAsserts && CurInfo.isValid()) {
-    const auto &Info = BlockInfo[MBB.getNumber()];
-    if (CurInfo != Info.Exit) {
-      LLVM_DEBUG(dbgs() << "in block " << printMBBReference(MBB) << "\n");
-      LLVM_DEBUG(dbgs() << "  begin        state: " << Info.Pred << "\n");
-      LLVM_DEBUG(dbgs() << "  expected end state: " << Info.Exit << "\n");
-      LLVM_DEBUG(dbgs() << "  actual   end state: " << CurInfo << "\n");
-    }
-    assert(CurInfo == Info.Exit &&
-           "InsertVSETVLI dataflow invariant violated");
+  const auto &Info = BlockInfo[MBB.getNumber()];
+  if (CurInfo != Info.Exit) {
+    LLVM_DEBUG(dbgs() << "in block " << printMBBReference(MBB) << "\n");
+    LLVM_DEBUG(dbgs() << "  begin        state: " << Info.Pred << "\n");
+    LLVM_DEBUG(dbgs() << "  expected end state: " << Info.Exit << "\n");
+    LLVM_DEBUG(dbgs() << "  actual   end state: " << CurInfo << "\n");
   }
+  assert(CurInfo == Info.Exit &&
+         "InsertVSETVLI dataflow invariant violated");
 }
 
 /// Perform simple partial redundancy elimination of the VSETVLI instructions

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[wangpc-pp]

LGTM.