Try both ways to fold an add together. This allows us to generate this code

        imul %EAX, %EAX, 400
        add %ECX, %EAX
        add %ESI, DWORD PTR [%ECX + 4*%EDX]
        inc %EDX
        cmp %EDX, 100

instead of this:

        imul %EAX, %EAX, 400
        add %ECX, %EAX
        mov %EAX, %EDX
        shl %EAX, 2
        add %ECX, %EAX
        add %ESI, DWORD PTR [%ECX]
        inc %EDX
        cmp %EDX, 100

llvm-svn: 19513

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelPattern.cpp b/llvm/lib/Target/X86/X86ISelPattern.cpp
index b3a93b11e40..194c2fa517c 100644
--- a/llvm/lib/Target/X86/X86ISelPattern.cpp
+++ b/llvm/lib/Target/X86/X86ISelPattern.cpp
@@ -527,6 +527,10 @@ bool ISel::SelectAddress(SDOperand N, X86AddressMode &AM) {
         !SelectAddress(N.Val->getOperand(1), AM))
       return false;
     AM = Backup;
+    if (!SelectAddress(N.Val->getOperand(1), AM) &&
+        !SelectAddress(N.Val->getOperand(0), AM))
+      return false;
+    AM = Backup;
     break;
   }
   }