diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Target/README.txt | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt index 3c689dbe46..518c9893c8 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -1252,3 +1252,24 @@ have the concept of a "C signed subtraction" operator that which is undefined 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. + + |