[llvm-commits] [llvm] r122695 - in /llvm/trunk: lib/Transforms/Utils/LoopSimplify.cpp test/Transforms/LoopSimplify/2010-12-26-PHIInfiniteLoop.ll

[Duncan Sands]

Author: baldrick
Date: Sun Jan  2 07:38:21 2011
New Revision: 122695

URL: http://llvm.org/viewvc/llvm-project?rev=122695&view=rev
Log:
Fix PR8702 by not having LoopSimplify claim to preserve LCSSA form.  As described
in the PR, the pass could break LCSSA form when inserting preheaders.  It probably
would be easy enough to fix this, but since currently we always go into LCSSA form
after running this pass, doing so is not urgent.

Added:
    llvm/trunk/test/Transforms/LoopSimplify/2010-12-26-PHIInfiniteLoop.ll
Modified:
    llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp

Modified: llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp?rev=122695&r1=122694&r2=122695&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp Sun Jan  2 07:38:21 2011
@@ -91,7 +91,6 @@
       AU.addPreserved<ScalarEvolution>();
       AU.addPreservedID(BreakCriticalEdgesID);  // No critical edges added.
       AU.addPreserved<DominanceFrontier>();
-      AU.addPreservedID(LCSSAID);
     }
 
     /// verifyAnalysis() - Verify LoopSimplifyForm's guarantees.
@@ -269,12 +268,11 @@
   PHINode *PN;
   for (BasicBlock::iterator I = L->getHeader()->begin();
        (PN = dyn_cast<PHINode>(I++)); )
-    if (Value *V = SimplifyInstruction(PN, 0, DT))
-      if (LI->replacementPreservesLCSSAForm(PN, V)) {
-          if (AA) AA->deleteValue(PN);
-          PN->replaceAllUsesWith(V);
-          PN->eraseFromParent();
-      }
+    if (Value *V = SimplifyInstruction(PN, 0, DT)) {
+      if (AA) AA->deleteValue(PN);
+      PN->replaceAllUsesWith(V);
+      PN->eraseFromParent();
+    }
 
   // If this loop has multiple exits and the exits all go to the same
   // block, attempt to merge the exits. This helps several passes, such
@@ -450,14 +448,13 @@
   for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
     PHINode *PN = cast<PHINode>(I);
     ++I;
-    if (Value *V = SimplifyInstruction(PN, 0, DT))
-      if (LI->replacementPreservesLCSSAForm(PN, V)) {
-        // This is a degenerate PHI already, don't modify it!
-        PN->replaceAllUsesWith(V);
-        if (AA) AA->deleteValue(PN);
-        PN->eraseFromParent();
-        continue;
-      }
+    if (Value *V = SimplifyInstruction(PN, 0, DT)) {
+      // This is a degenerate PHI already, don't modify it!
+      PN->replaceAllUsesWith(V);
+      if (AA) AA->deleteValue(PN);
+      PN->eraseFromParent();
+      continue;
+    }
 
     // Scan this PHI node looking for a use of the PHI node by itself.
     for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)

Added: llvm/trunk/test/Transforms/LoopSimplify/2010-12-26-PHIInfiniteLoop.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopSimplify/2010-12-26-PHIInfiniteLoop.ll?rev=122695&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopSimplify/2010-12-26-PHIInfiniteLoop.ll (added)
+++ llvm/trunk/test/Transforms/LoopSimplify/2010-12-26-PHIInfiniteLoop.ll Sun Jan  2 07:38:21 2011
@@ -0,0 +1,43 @@
+; RUN: opt < %s -loopsimplify -S
+; PR8702
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-freebsd9.0"
+
+declare void @foo(i32 %x)
+
+define fastcc void @inm_merge() nounwind {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %while.cond36.i, %entry
+  br i1 undef, label %do.body, label %for.body
+
+for.body:                                         ; preds = %for.cond
+  br i1 undef, label %while.cond36.i, label %if.end44
+
+if.end44:                                         ; preds = %for.body
+  %call49 = call fastcc i32 @inm_get_source()
+  br i1 undef, label %if.end54, label %for.cond64
+
+if.end54:                                         ; preds = %if.end44
+  br label %while.cond36.i
+
+while.cond36.i:                                   ; preds = %if.end54, %for.body
+  br label %for.cond
+
+for.cond64:                                       ; preds = %if.end88, %for.cond64, %if.end44
+  %error.161 = phi i32 [ %error.161, %for.cond64 ], [ %error.161, %if.end88 ], [ %call49, %if.end44 ]
+  call void @foo(i32 %error.161)
+  br i1 undef, label %for.cond64, label %if.end88
+
+if.end88:                                         ; preds = %for.cond64
+  br i1 undef, label %for.cond64, label %if.end98
+
+if.end98:                                         ; preds = %if.end88
+  unreachable
+
+do.body:                                          ; preds = %for.cond
+  unreachable
+}
+
+declare fastcc i32 @inm_get_source() nounwind