[llvm-commits] [llvm] r60404 - /llvm/trunk/lib/Target/README.txt

[Chris Lattner]

Author: lattner
Date: Tue Dec  2 00:32:34 2008
New Revision: 60404

URL: http://llvm.org/viewvc/llvm-project?rev=60404&view=rev
Log:
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Modified:
    llvm/trunk/lib/Target/README.txt

Modified: llvm/trunk/lib/Target/README.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/README.txt?rev=60404&r1=60403&r2=60404&view=diff

==============================================================================
--- llvm/trunk/lib/Target/README.txt (original)
+++ llvm/trunk/lib/Target/README.txt Tue Dec  2 00:32:34 2008
@@ -1252,3 +1252,24 @@
 on overflow.
 
 //===---------------------------------------------------------------------===//
+
+This was noticed in the entryblock for grokdeclarator in 403.gcc:
+
+        %tmp = icmp eq i32 %decl_context, 4          
+        %decl_context_addr.0 = select i1 %tmp, i32 3, i32 %decl_context 
+        %tmp1 = icmp eq i32 %decl_context_addr.0, 1 
+        %decl_context_addr.1 = select i1 %tmp1, i32 0, i32 %decl_context_addr.0
+
+tmp1 should be simplified to something like:
+  (!tmp || decl_context == 1)
+
+This allows recursive simplifications, tmp1 is used all over the place in
+the function, e.g. by:
+
+        %tmp23 = icmp eq i32 %decl_context_addr.1, 0            ; <i1> [#uses=1]
+        %tmp24 = xor i1 %tmp1, true             ; <i1> [#uses=1]
+        %or.cond8 = and i1 %tmp23, %tmp24               ; <i1> [#uses=1]
+
+later.
+
+