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| author | Eric Botcazou <ebotcazou@adacore.com> | 2015-09-17 15:35:24 +0000 |
|---|---|---|
| committer | Eric Botcazou <ebotcazou@gcc.gnu.org> | 2015-09-17 15:35:24 +0000 |
| commit | 308fbc42903ba2f97c29eea52928802686a917f1 (patch) | |
| tree | c12e12796ec6015809c220ba206a9730a7d23acb /gcc/df-problems.c | |
| parent | 01610fec498c0ed7a2d1377a3a2a960172355a4b (diff) | |
re PR rtl-optimization/66790 (Invalid uninitialized register handling in REE)
PR rtl-optimization/66790
* df-problems.c (LIVE): Amend documentation.
From-SVN: r227874
Diffstat (limited to 'gcc/df-problems.c')
| -rw-r--r-- | gcc/df-problems.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/gcc/df-problems.c b/gcc/df-problems.c index 0ab533fe0b1..153732ae26f 100644 --- a/gcc/df-problems.c +++ b/gcc/df-problems.c @@ -1309,22 +1309,23 @@ df_lr_verify_transfer_functions (void) /*---------------------------------------------------------------------------- - LIVE AND MUST-INITIALIZED REGISTERS. + LIVE AND MAY-INITIALIZED REGISTERS. This problem first computes the IN and OUT bitvectors for the - must-initialized registers problems, which is a forward problem. - It gives the set of registers for which we MUST have an available - definition on any path from the entry block to the entry/exit of - a basic block. Sets generate a definition, while clobbers kill + may-initialized registers problems, which is a forward problem. + It gives the set of registers for which we MAY have an available + definition, i.e. for which there is an available definition on + at least one path from the entry block to the entry/exit of a + basic block. Sets generate a definition, while clobbers kill a definition. In and out bitvectors are built for each basic block and are indexed by regnum (see df.h for details). In and out bitvectors in struct - df_live_bb_info actually refers to the must-initialized problem; + df_live_bb_info actually refers to the may-initialized problem; Then, the in and out sets for the LIVE problem itself are computed. These are the logical AND of the IN and OUT sets from the LR problem - and the must-initialized problem. + and the may-initialized problem. ----------------------------------------------------------------------------*/ /* Private data used to verify the solution for this problem. */ @@ -1531,7 +1532,7 @@ df_live_confluence_n (edge e) } -/* Transfer function for the forwards must-initialized problem. */ +/* Transfer function for the forwards may-initialized problem. */ static bool df_live_transfer_function (int bb_index) @@ -1555,7 +1556,7 @@ df_live_transfer_function (int bb_index) } -/* And the LR info with the must-initialized registers, to produce the LIVE info. */ +/* And the LR info with the may-initialized registers to produce the LIVE info. */ static void df_live_finalize (bitmap all_blocks) |