[PATCH] D104868: [ARM] Fix crash in chained BFI combine due to incorrectly RAUW'ing a node.

[Amara Emerson via Phabricator via llvm-commits]

aemerson updated this revision to Diff 354332.
aemerson added a comment.

Rework test.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104868/new/

https://reviews.llvm.org/D104868

Files:
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/test/CodeGen/ARM/bfi-chain-cse-crash.ll


Index: llvm/test/CodeGen/ARM/bfi-chain-cse-crash.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/ARM/bfi-chain-cse-crash.ll
@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=thumbv7s | FileCheck %s
+target datalayout = "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
+target triple = "thumbv7s-apple-ios3.1.3"
+
+define void @bfi_chain_cse_crash(i8* %0, i8 *%ptr) {
+; CHECK-LABEL: bfi_chain_cse_crash:
+; CHECK:       @ %bb.0: @ %entry
+; CHECK-NEXT:    ldrb r2, [r0]
+; CHECK-NEXT:    and r3, r2, #1
+; CHECK-NEXT:    lsr.w r12, r2, #3
+; CHECK-NEXT:    bfi r3, r12, #3, #1
+; CHECK-NEXT:    strb r3, [r0]
+; CHECK-NEXT:    and r0, r2, #4
+; CHECK-NEXT:    bfi r0, r12, #3, #1
+; CHECK-NEXT:    strb r0, [r1]
+; CHECK-NEXT:    bx lr
+entry:
+  %1 = load i8, i8* %0, align 1
+  %2 = and i8 %1, 1
+  %3 = select i1 false, i8 %2, i8 0
+  %4 = and i8 %1, 4
+  %5 = icmp eq i8 %4, 0
+  %6 = zext i8 %3 to i32
+  %7 = or i32 %6, 4
+  %8 = trunc i32 %7 to i8
+  %9 = select i1 %5, i8 %3, i8 %8
+  %10 = and i8 %1, 8
+  %11 = icmp eq i8 %10, 0
+  %12 = zext i8 %2 to i32
+  %13 = or i32 %12, 8
+  %14 = trunc i32 %13 to i8
+  %15 = zext i8 %9 to i32
+  %16 = or i32 %15, 8
+  %17 = trunc i32 %16 to i8
+  %18 = select i1 %11, i8 %2, i8 %14
+  %19 = select i1 %11, i8 %9, i8 %17
+  store i8 %18, i8* %0, align 1
+  store i8 %19, i8* %ptr, align 1
+  ret void
+}
Index: llvm/lib/Target/ARM/ARMISelLowering.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -14035,9 +14035,7 @@
     assert(From1 == From2);
     (void)From2;
 
-    // First, unlink CombineBFI.
-    DCI.DAG.ReplaceAllUsesWith(CombineBFI, CombineBFI.getOperand(0));
-    // Then create a new BFI, combining the two together.
+    // Create a new BFI, combining the two together.
     APInt NewFromMask = FromMask1 | FromMask2;
     APInt NewToMask = ToMask1 | ToMask2;
 
@@ -14046,9 +14044,9 @@
 
     if (NewFromMask[0] == 0)
       From1 = DCI.DAG.getNode(
-        ISD::SRL, dl, VT, From1,
-        DCI.DAG.getConstant(NewFromMask.countTrailingZeros(), dl, VT));
-    return DCI.DAG.getNode(ARMISD::BFI, dl, VT, N->getOperand(0), From1,
+          ISD::SRL, dl, VT, From1,
+          DCI.DAG.getConstant(NewFromMask.countTrailingZeros(), dl, VT));
+    return DCI.DAG.getNode(ARMISD::BFI, dl, VT, CombineBFI.getOperand(0), From1,
                            DCI.DAG.getConstant(~NewToMask, dl, VT));
   }
   return SDValue();


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