[PATCH] D112228: [RISCV] Fix missing cross-block VSETVLI insertion

[Fraser Cormack via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG74c6895b39e3: [RISCV] Fix missing cross-block VSETVLI insertion (authored by frasercrmck).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112228/new/

https://reviews.llvm.org/D112228

Files:
  llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
  llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.mir


Index: llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.mir
===================================================================
--- llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.mir
+++ llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.mir
@@ -442,10 +442,6 @@
 
 ...
 ---
-# FIXME: We incorrectly merge info for %bb.1 into that for %bb.0, leading us to
-# skip a vsetvli for the PseudoVADD_VX_MF2 in %bb.3. In fact, the
-# PseudoVPOPC_M_B1 is given a vsetvli (e8,mf8) which, if control flow flows
-# through %bb.1 to %bb.3, misconfigures the PseudoVADD_VX_MF2.
 name:            vsetvli_vpopc
 tracksRegLiveness: true
 registers:
@@ -495,6 +491,7 @@
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.3:
   ; CHECK-NEXT:   [[PHI:%[0-9]+]]:gpr = PHI [[DEF]], %bb.1, [[LWU]], %bb.2
+  ; CHECK-NEXT:   dead $x0 = PseudoVSETVLIX0 killed $x0, 87, implicit-def $vl, implicit-def $vtype, implicit $vl
   ; CHECK-NEXT:   [[PseudoVADD_VX_MF2_:%[0-9]+]]:vr = nsw PseudoVADD_VX_MF2 [[PseudoVLE32_V_MF2_MASK]], [[PHI]], -1, 5, implicit $vl, implicit $vtype
   ; CHECK-NEXT:   $v0 = COPY [[PseudoVADD_VX_MF2_]]
   ; CHECK-NEXT:   PseudoRET implicit $v0
Index: llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
+++ llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
@@ -181,7 +181,7 @@
   // Determine whether the vector instructions requirements represented by
   // InstrInfo are compatible with the previous vsetvli instruction represented
   // by this.
-  bool isCompatible(const VSETVLIInfo &InstrInfo) const {
+  bool isCompatible(const VSETVLIInfo &InstrInfo, bool Strict) const {
     assert(isValid() && InstrInfo.isValid() &&
            "Can't compare invalid VSETVLIInfos");
     assert(!InstrInfo.SEWLMULRatioOnly &&
@@ -196,7 +196,8 @@
 
     // If the instruction doesn't need an AVLReg and the SEW matches, consider
     // it compatible.
-    if (InstrInfo.hasAVLReg() && InstrInfo.AVLReg == RISCV::NoRegister) {
+    if (!Strict && InstrInfo.hasAVLReg() &&
+        InstrInfo.AVLReg == RISCV::NoRegister) {
       if (SEW == InstrInfo.SEW)
         return true;
     }
@@ -209,6 +210,10 @@
     if (hasSameVTYPE(InstrInfo))
       return true;
 
+    // Strict matches must ensure a full VTYPE match.
+    if (Strict)
+      return false;
+
     // If this is a mask reg operation, it only cares about VLMAX.
     // FIXME: Mask reg operations are probably ok if "this" VLMAX is larger
     // than "InstrInfo".
@@ -317,7 +322,7 @@
 
     // If the change is compatible with the input, we won't create a VSETVLI
     // and should keep the predecessor.
-    if (isCompatible(Other))
+    if (isCompatible(Other, /*Strict*/ true))
       return *this;
 
     // Otherwise just use whatever is in this block.
@@ -550,7 +555,7 @@
 
 bool RISCVInsertVSETVLI::needVSETVLI(const VSETVLIInfo &Require,
                                      const VSETVLIInfo &CurInfo) {
-  if (CurInfo.isCompatible(Require))
+  if (CurInfo.isCompatible(Require, /*Strict*/ false))
     return false;
 
   // We didn't find a compatible value. If our AVL is a virtual register,


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