[PATCH] D40184: [LICM] Fix PR35342

[Jun Bum Lim via Phabricator via llvm-commits]

junbuml created this revision.

This change fix PR35342 by rebuilding user_iterator which is invalidated after replacing users with undef in unreachable blocks.


https://reviews.llvm.org/D40184

Files:
  lib/Transforms/Scalar/LICM.cpp
  test/Transforms/LICM/pr35342.ll


Index: test/Transforms/LICM/pr35342.ll
===================================================================
--- /dev/null
+++ test/Transforms/LICM/pr35342.ll
@@ -0,0 +1,27 @@
+; RUN: opt -licm -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-LABEL: @f1
+; CHECK-LABEL: bci_524:
+; CHECK: add i32 undef, undef
+define void @f1(i32 %v) {
+not_zero.lr.ph:
+  br label %not_zero
+
+not_zero:
+  br i1 undef, label %bci_748 ,  label %bci_314
+
+bci_314:
+  %0 = select i1 undef, i32 undef, i32 undef
+  br label %not_zero
+
+bci_524:                   ; No predecessors!
+  %add = add i32 %0, %0
+  br label %bci_748
+
+bci_748:
+  ret void
+}
+
Index: lib/Transforms/Scalar/LICM.cpp
===================================================================
--- lib/Transforms/Scalar/LICM.cpp
+++ lib/Transforms/Scalar/LICM.cpp
@@ -907,6 +907,8 @@
 
     if (!DT->isReachableFromEntry(User->getParent())) {
       User->replaceUsesOfWith(&I, UndefValue::get(I.getType()));
+      UI = I.user_begin();
+      UE = I.user_end();
       continue;
     }
 
@@ -919,6 +921,8 @@
     BasicBlock *BB = PN->getIncomingBlock(U);
     if (!DT->isReachableFromEntry(BB)) {
       U = UndefValue::get(I.getType());
+      UI = I.user_begin();
+      UE = I.user_end();
       continue;
     }
 


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