[llvm-commits] [llvm] r172576 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineVectorOps.cpp test/Transforms/InstCombine/vec_extract_elt.ll

[Nadav Rotem]

Author: nadav
Date: Tue Jan 15 17:43:14 2013
New Revision: 172576

URL: http://llvm.org/viewvc/llvm-project?rev=172576&view=rev
Log:
Teach InstCombine to optimize extract of a value from a vector add operation with a constant zero.


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
    llvm/trunk/test/Transforms/InstCombine/vec_extract_elt.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp?rev=172576&r1=172575&r2=172576&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineVectorOps.cpp Tue Jan 15 17:43:14 2013
@@ -13,7 +13,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "InstCombine.h"
+#include "llvm/Support/PatternMatch.h"
 using namespace llvm;
+using namespace PatternMatch;
 
 /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
 /// is to leave as a vector operation.  isConstant indicates whether we're
@@ -92,6 +94,13 @@
     return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
   }
 
+  // Extract a value from a vector add operation with a constant zero.
+  Value *Val = 0; Constant *Con = 0;
+  if (match(V, m_Add(m_Value(Val), m_Constant(Con)))) {
+    if (Con->getAggregateElement(EltNo)->isNullValue())
+      return FindScalarElement(Val, EltNo);
+  }
+
   // Otherwise, we don't know.
   return 0;
 }

Modified: llvm/trunk/test/Transforms/InstCombine/vec_extract_elt.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/vec_extract_elt.ll?rev=172576&r1=172575&r2=172576&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/vec_extract_elt.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/vec_extract_elt.ll Tue Jan 15 17:43:14 2013
@@ -7,3 +7,13 @@
         ret i32 %tmp19
 }
 
+define i64 @test2(i64 %in) {
+  %vec = insertelement <8 x i64> undef, i64 %in, i32 0
+  %splat = shufflevector <8 x i64> %vec, <8 x i64> undef, <8 x i32> zeroinitializer
+  %add = add <8 x i64> %splat, <i64 0, i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7>
+  %scl1 = extractelement <8 x i64> %add, i32 0
+  %scl2 = extractelement <8 x i64> %add, i32 0
+  %r = add i64 %scl1, %scl2
+  ret i64 %r
+}
+