[llvm-commits] [llvm] r51263 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/add2.ll

[Chris Lattner]

Author: lattner
Date: Mon May 19 15:01:56 2008
New Revision: 51263

URL: http://llvm.org/viewvc/llvm-project?rev=51263&view=rev
Log:
be more aggressive about transforming add -> or when the operands have no
intersecting bits.  This triggers all over the place, for example in lencode,
with adds of stuff like:

	%tmp580 = mul i32 %tmp579, 2	
	%tmp582 = and i32 %b8, 1
and

	%tmp28 = shl i32 %abs.i, 1		
	%sign.0 = select i1 %tmp23, i32 1, i32 0
and
	%tmp344 = shl i32 %tmp343, 2	
	%tmp346 = and i32 %tmp96, 3

etc.



Modified:
    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
    llvm/trunk/test/Transforms/InstCombine/add2.ll

Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=51263&r1=51262&r2=51263&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Mon May 19 15:01:56 2008
@@ -2503,6 +2503,25 @@
   if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
     if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
       return R;
+  
+  // A+B --> A|B iff A and B have no bits set in common.
+  if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
+    APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
+    APInt LHSKnownOne(IT->getBitWidth(), 0);
+    APInt LHSKnownZero(IT->getBitWidth(), 0);
+    ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
+    if (LHSKnownZero != 0) {
+      APInt RHSKnownOne(IT->getBitWidth(), 0);
+      APInt RHSKnownZero(IT->getBitWidth(), 0);
+      ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
+      
+      // No bits in common -> bitwise or.
+      if ((LHSKnownZero|RHSKnownZero).isAllOnesValue()) {
+        cerr << "HACK\n" << *LHS << *RHS << "\n";
+        return BinaryOperator::CreateOr(LHS, RHS);
+      }
+    }
+  }
 
   // W*X + Y*Z --> W * (X+Z)  iff W == Y
   if (I.getType()->isIntOrIntVector()) {

Modified: llvm/trunk/test/Transforms/InstCombine/add2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/add2.ll?rev=51263&r1=51262&r2=51263&view=diff

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/add2.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/add2.ll Mon May 19 15:01:56 2008
@@ -29,3 +29,18 @@
 
 declare i32 @callee(i32)
 
+
+define i32 @test3(i32 %A) {
+  %B = and i32 %A, 7
+  %C = and i32 %A, 32
+  %F = add i32 %B, %C
+  ret i32 %F
+}
+
+define i32 @test4(i32 %A) {
+  %B = and i32 %A, 128
+  %C = lshr i32 %A, 30
+  %F = add i32 %B, %C
+  ret i32 %F
+}
+