Fold certain additions through selects (and their compares) so as to eliminate subtractions. This code is often produced by the SMAX expansion in SCEV.

This implements test/Transforms/InstCombine/2007-12-18-AddSelCmpSub.ll

llvm-svn: 45158

1 files changed, 0 insertions, 18 deletions

diff --git a/llvm/lib/Target/README.txt b/llvm/lib/Target/README.txt
index c942d944712..37c0a359a2b 100644
--- a/llvm/lib/Target/README.txt
+++ b/llvm/lib/Target/README.txt
@@ -464,21 +464,3 @@ entry:
 }
 
 //===---------------------------------------------------------------------===//
-
-This code is often produced by the SMAX expansion in SCEV:
-
-define i32 @foo(i32 %a) {
-entry:
-        %tmp15 = sub i32 99, %a         ; <i32> [#uses=2]
-        %tmp16 = icmp slt i32 %tmp15, 0         ; <i1> [#uses=1]
-        %smax = select i1 %tmp16, i32 0, i32 %tmp15             ; <i32> [#uses=1]
-        %tmp12 = add i32 %smax, %a              ; <i32> [#uses=1]
-        %tmp13 = add i32 %tmp12, 1              ; <i32> [#uses=1]
-        ret i32 %tmp13
-}
-
-Note that the tmp12 add can be pushed through the select operands, turning
-it into a "select %tmp16, %a, 99".  We apparently already do this in dag 
-combine because it isn't present in X86 output.
-
-//===---------------------------------------------------------------------===//