[PATCH] [ValueTracking] Fix PR23011.

[Nick Lewycky]

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Comment at: lib/Analysis/ValueTracking.cpp:1937
@@ +1936,3 @@
+      // the number of sign bits is MIN(CLZ(C-1), CLO(-C+1)).
+      //
+
----------------
Blank comment line.

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Comment at: lib/Analysis/ValueTracking.cpp:1941
@@ -1935,1 +1940,3 @@
+      unsigned WhenNegative = (-(*Denominator) + 1).countLeadingOnes();
+      unsigned ResBits = std::min(WhenPositive, WhenNegative);
 
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Is this ever different from Denominator.ceilLogBase2()?

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Comment at: test/Analysis/ValueTracking/pr230011.ll:1
@@ +1,2 @@
+; RUN: opt -indvars -S < %s | FileCheck %s
+
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File name is off "pr230011.ll" should be "pr23011.ll".

Also, if this is a bug in value tracking, isn't there a more direct way to observe it than this? Maybe just srem + and and then opt -instsimplify?

http://reviews.llvm.org/D8600

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