diff options
Diffstat (limited to 'gcc/doc/tree-ssa.texi')
| -rw-r--r-- | gcc/doc/tree-ssa.texi | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/gcc/doc/tree-ssa.texi b/gcc/doc/tree-ssa.texi index dc6a111..25aa006 100644 --- a/gcc/doc/tree-ssa.texi +++ b/gcc/doc/tree-ssa.texi @@ -355,7 +355,7 @@ FOR_EACH_PHI_OR_STMT_DEF (def_operand_p, phi, iter, flags) Immediate use information is now always available. Using the immediate use iterators, you may examine every use of any @code{SSA_NAME}. For instance, -to change each use of @code{ssa_var} to @code{ssa_var2} and call fold_stmt on +to change each use of @code{ssa_var} to @code{val} and call fold_stmt on each stmt after that is done: @smallexample @@ -367,8 +367,9 @@ each stmt after that is done: FOR_EACH_IMM_USE_STMT (stmt, iterator, ssa_var) @{ FOR_EACH_IMM_USE_ON_STMT (imm_use_p, iterator) - SET_USE (imm_use_p, ssa_var_2); + SET_USE (imm_use_p, val); fold_stmt (stmt); + update_stmt (stmt); @} @end smallexample @@ -389,9 +390,7 @@ terminated early; a destructor takes care of that when leaving the @code{FOR_EACH_IMM_USE_STMT} scope. There are checks in @code{verify_ssa} which verify that the immediate use list -is up to date, as well as checking that an optimization didn't break from the -loop without using this macro. It is safe to simply 'break'; from a -@code{FOR_EACH_IMM_USE_FAST} traverse. +is up to date. Some useful functions and macros: @enumerate @@ -412,7 +411,9 @@ isn't located in a @code{PHI} node. @end enumerate Note that uses are not put into an immediate use list until their statement is -actually inserted into the instruction stream via a @code{bsi_*} routine. +actually inserted into the instruction stream via a @code{gsi_*} routine +which calls @code{update_stmt} to re-scan SSA operands and update the +immediate use lists. It is also still possible to utilize lazy updating of statements, but this should be used only when absolutely required. Both alias analysis and the |