[llvm-commits] [llvm] r100748 - in /llvm/trunk: lib/Transforms/Scalar/LoopStrengthReduce.cpp test/CodeGen/X86/multiple-loop-post-inc.ll

[Dan Gohman]

Author: djg
Date: Thu Apr  8 00:57:57 2010
New Revision: 100748

URL: http://llvm.org/viewvc/llvm-project?rev=100748&view=rev
Log:
When expanding expressions which are using post-inc mode for multiple loops,
ensure that the expansion is dominated by the increments of those loops.

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
    llvm/trunk/test/CodeGen/X86/multiple-loop-post-inc.ll

Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=100748&r1=100747&r2=100748&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Thu Apr  8 00:57:57 2010
@@ -2820,6 +2820,22 @@
     else
       Inputs.push_back(IVIncInsertPos);
   }
+  // The expansion must also be dominated by the increment positions of any
+  // loops it for which it is using post-inc mode.
+  for (PostIncLoopSet::const_iterator I = LF.PostIncLoops.begin(),
+       E = LF.PostIncLoops.end(); I != E; ++I) {
+    const Loop *PIL = *I;
+    if (PIL == L) continue;
+
+    SmallVector<BasicBlock *, 4> ExitingBlocks;
+    PIL->getExitingBlocks(ExitingBlocks);
+    if (!ExitingBlocks.empty()) {
+      BasicBlock *BB = ExitingBlocks[0];
+      for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i)
+        BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]);
+      Inputs.push_back(BB->getTerminator());
+    }
+  }
 
   // Then, climb up the immediate dominator tree as far as we can go while
   // still being dominated by the input positions.

Modified: llvm/trunk/test/CodeGen/X86/multiple-loop-post-inc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/multiple-loop-post-inc.ll?rev=100748&r1=100747&r2=100748&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/multiple-loop-post-inc.ll (original)
+++ llvm/trunk/test/CodeGen/X86/multiple-loop-post-inc.ll Thu Apr  8 00:57:57 2010
@@ -275,3 +275,30 @@
 return:                                           ; preds = %entry
   ret void
 }
+
+; Codegen shouldn't crash on this testcase.
+
+define void @bar(i32 %a, i32 %b) nounwind {
+entry:                           ; preds = %bb1, %entry, %for.end204
+  br label %outer
+
+outer:                                     ; preds = %bb1, %entry
+  %i6 = phi i32 [ %storemerge171, %bb1 ], [ %a, %entry ] ; <i32> [#uses=2]
+  %storemerge171 = add i32 %i6, 1      ; <i32> [#uses=1]
+  br label %inner
+
+inner:                                       ; preds = %bb0, %if.end275
+  %i8 = phi i32 [ %a, %outer ], [ %indvar.next159, %bb0 ] ; <i32> [#uses=2]
+  %t338 = load i32* undef                     ; <i32> [#uses=1]
+  %t191 = mul i32 %i8, %t338        ; <i32> [#uses=1]
+  %t179 = add i32 %i6, %t191        ; <i32> [#uses=1]
+  br label %bb0
+
+bb0:                                     ; preds = %for.body332
+  %indvar.next159 = add i32 %i8, 1     ; <i32> [#uses=1]
+  br i1 undef, label %bb1, label %inner
+
+bb1:                                     ; preds = %bb0, %outer
+  %midx.4 = phi i32 [ %t179, %bb0 ] ; <i32> [#uses=0]
+  br label %outer
+}