[PATCH] D126574: [RISCV] Fix an inconsistency with compatible load/store handling

[Philip Reames via Phabricator via llvm-commits]

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Once we've computed the incoming predecessor state, we can use the same compatibility check to decide if we need to insert a vsetvli before it.  We in fact did this during the data flow (phase 1 and 2), but skipped doing when using the result (phase 3).

The test changes show minor improvements, but the actual motivation is to fix a case where strict-asserts fail.  I haven't yet managed to reduce a test case down to anything sensible, will update if I manage.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D126574

Files:
  llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
  llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll
  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
@@ -941,8 +941,8 @@
   ; CHECK-NEXT:   successors: %bb.3(0x80000000)
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT:   [[ADD1:%[0-9]+]]:gpr = ADD %src, [[PHI]]
-  ; CHECK-NEXT:   dead $x0 = PseudoVSETVLIX0 killed $x0, 69 /* e8, mf8, ta, mu */, implicit-def $vl, implicit-def $vtype, implicit $vl
   ; CHECK-NEXT:   [[PseudoVLE8_V_MF8_:%[0-9]+]]:vrnov0 = PseudoVLE8_V_MF8 killed [[ADD1]], -1, 3 /* e8 */, implicit $vl, implicit $vtype
+  ; CHECK-NEXT:   dead $x0 = PseudoVSETVLIX0 killed $x0, 69 /* e8, mf8, ta, mu */, implicit-def $vl, implicit-def $vtype, implicit $vl
   ; CHECK-NEXT:   [[PseudoVADD_VI_MF8_:%[0-9]+]]:vrnov0 = PseudoVADD_VI_MF8 [[PseudoVLE8_V_MF8_]], 4, -1, 3 /* e8 */, implicit $vl, implicit $vtype
   ; CHECK-NEXT:   [[ADD2:%[0-9]+]]:gpr = ADD %dst, [[PHI]]
   ; CHECK-NEXT:   PseudoVSE8_V_MF8 killed [[PseudoVADD_VI_MF8_]], killed [[ADD2]], -1, 3 /* e8 */, implicit $vl, implicit $vtype
Index: llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll
===================================================================
--- llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll
+++ llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll
@@ -505,8 +505,8 @@
 ; CHECK-NEXT:    andi a0, a3, 1
 ; CHECK-NEXT:    beqz a0, .LBB9_2
 ; CHECK-NEXT:  # %bb.1: # %if
-; CHECK-NEXT:    vsetvli zero, zero, e16, mf2, ta, mu
 ; CHECK-NEXT:    vle16.v v10, (a1)
+; CHECK-NEXT:    vsetvli zero, zero, e16, mf2, ta, mu
 ; CHECK-NEXT:    vwcvt.x.x.v v8, v10
 ; CHECK-NEXT:  .LBB9_2: # %if.end
 ; CHECK-NEXT:    vsetvli zero, zero, e32, m1, ta, mu
@@ -544,8 +544,8 @@
 ; CHECK-NEXT:    andi a0, a4, 1
 ; CHECK-NEXT:    beqz a0, .LBB10_2
 ; CHECK-NEXT:  # %bb.1: # %if
-; CHECK-NEXT:    vsetvli zero, zero, e16, mf2, ta, mu
 ; CHECK-NEXT:    vle16.v v10, (a1)
+; CHECK-NEXT:    vsetvli zero, zero, e16, mf2, ta, mu
 ; CHECK-NEXT:    vwadd.wv v9, v9, v10
 ; CHECK-NEXT:  .LBB10_2: # %if.end
 ; CHECK-NEXT:    andi a0, a5, 1
Index: llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
+++ llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
@@ -1123,7 +1123,7 @@
         // use the predecessor information.
         CurInfo = BlockInfo[MBB.getNumber()].Pred;
         assert(CurInfo.isValid() && "Expected a valid predecessor state.");
-        if (needVSETVLI(NewInfo, CurInfo)) {
+        if (needVSETVLI(MI, NewInfo, CurInfo)) {
           // If this is the first implicit state change, and the state change
           // requested can be proven to produce the same register contents, we
           // can skip emitting the actual state change and continue as if we


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