[llvm] r340540 - [x86] add debug option for and-immediate shrinking

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Thu Aug 23 08:58:07 2018
New Revision: 340540

URL: http://llvm.org/viewvc/llvm-project?rev=340540&view=rev
Log:
[x86] add debug option for and-immediate shrinking
  
The commit that added this functionality:
rL322957

may be causing/exposing a miscompile in PR38648:
https://bugs.llvm.org/show_bug.cgi?id=38648

so allow enabling/disabling to make debugging easier.


Modified:
    llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp?rev=340540&r1=340539&r2=340540&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp Thu Aug 23 08:58:07 2018
@@ -41,6 +41,10 @@ using namespace llvm;
 
 STATISTIC(NumLoadMoved, "Number of loads moved below TokenFactor");
 
+static cl::opt<bool> AndImmShrink("x86-and-imm-shrink", cl::init(true),
+    cl::desc("Enable setting constant bits to reduce size of mask immediates"),
+    cl::Hidden);
+
 //===----------------------------------------------------------------------===//
 //                      Pattern Matcher Implementation
 //===----------------------------------------------------------------------===//
@@ -2927,7 +2931,7 @@ void X86DAGToDAGISel::Select(SDNode *Nod
   case ISD::AND:
     if (matchBEXTRFromAnd(Node))
       return;
-    if (shrinkAndImmediate(Node))
+    if (AndImmShrink && shrinkAndImmediate(Node))
       return;
 
     LLVM_FALLTHROUGH;