[llvm-commits] [llvm] r125557 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp test/Transforms/InstCombine/2011-02-14-InfLoop.ll
Nadav Rotem
nadav.rotem at intel.com
Mon Feb 14 23:13:48 PST 2011
Author: nadav
Date: Tue Feb 15 01:13:48 2011
New Revision: 125557
URL: http://llvm.org/viewvc/llvm-project?rev=125557&view=rev
Log:
Fix 9216 - Endless loop in InstCombine pass.
The pattern "A&(A^B) -> A & ~B" recreated itself because ~B is
actually a xor -1.
Added:
llvm/trunk/test/Transforms/InstCombine/2011-02-14-InfLoop.ll (with props)
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=125557&r1=125556&r2=125557&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Tue Feb 15 01:13:48 2011
@@ -1140,7 +1140,11 @@
cast<BinaryOperator>(Op1)->swapOperands();
std::swap(A, B);
}
- if (A == Op0) // A&(A^B) -> A & ~B
+ // Notice that the patten (A&(~B)) is actually (A&(-1^B)), so if
+ // A is originally -1 (or a vector of -1 and undefs), then we enter
+ // an endless loop. By checking that A is non-constant we ensure that
+ // we will never get to the loop.
+ if (A == Op0 && !isa<Constant>(A)) // A&(A^B) -> A & ~B
return BinaryOperator::CreateAnd(A, Builder->CreateNot(B, "tmp"));
}
Added: llvm/trunk/test/Transforms/InstCombine/2011-02-14-InfLoop.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2011-02-14-InfLoop.ll?rev=125557&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/2011-02-14-InfLoop.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/2011-02-14-InfLoop.ll Tue Feb 15 01:13:48 2011
@@ -0,0 +1,19 @@
+; This testcase causes an infinite loop in the instruction combiner,
+; because it changes a pattern and the original pattern is almost
+; identical to the newly-generated pattern.
+; RUN: opt < %s -instcombine -disable-output
+
+;PR PR9216
+
+target triple = "x86_64-unknown-linux-gnu"
+
+define <4 x float> @m_387(i8* noalias nocapture %A, i8* nocapture %B, <4 x i1> %C) nounwind {
+entry:
+ %movcsext20 = sext <4 x i1> %C to <4 x i32>
+ %tmp2389 = xor <4 x i32> %movcsext20, <i32 -1, i32 -1, i32 -1, i32 -1>
+ %movcand25 = and <4 x i32> %tmp2389, <i32 undef, i32 undef, i32 undef, i32 -1>
+ %movcor26 = or <4 x i32> %movcand25, zeroinitializer
+ %L2 = bitcast <4 x i32> %movcor26 to <4 x float>
+ %L3 = shufflevector <4 x float> zeroinitializer, <4 x float> %L2, <4 x i32> <i32 0, i32 1, i32 2, i32 7>
+ ret <4 x float> %L3
+}
Propchange: llvm/trunk/test/Transforms/InstCombine/2011-02-14-InfLoop.ll
------------------------------------------------------------------------------
svn:eol-style = native
More information about the llvm-commits
mailing list