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| author | Michael D. Adams <t-madams@microsoft.com> | 2007-06-28 08:25:43 +0000 |
|---|---|---|
| committer | Michael D. Adams <t-madams@microsoft.com> | 2007-06-28 08:25:43 +0000 |
| commit | 81285ec475e94ef93d2ac59386d48cb333da2c96 (patch) | |
| tree | 24690976f6da38cc5da0843f0f7b47da7f7d2b62 /compiler/cmm/CmmBrokenBlock.hs | |
| parent | 61c73ae30a45d558815cf21272d13f2fa260519f (diff) | |
| download | haskell-81285ec475e94ef93d2ac59386d48cb333da2c96.tar.gz | |
Comment and formatting updates for the CPS pass
Diffstat (limited to 'compiler/cmm/CmmBrokenBlock.hs')
| -rw-r--r-- | compiler/cmm/CmmBrokenBlock.hs | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/compiler/cmm/CmmBrokenBlock.hs b/compiler/cmm/CmmBrokenBlock.hs index a968484b44..af47e8d559 100644 --- a/compiler/cmm/CmmBrokenBlock.hs +++ b/compiler/cmm/CmmBrokenBlock.hs @@ -19,6 +19,11 @@ import Panic import Unique import UniqFM +-- This module takes a 'CmmBasicBlock' which might have 'CmmCall' +-- statements in it with 'CmmSafe' set and breaks it up at each such call. +-- It also collects information about the block for later use +-- by the CPS algorithm. + ----------------------------------------------------------------------------- -- Data structures ----------------------------------------------------------------------------- @@ -110,6 +115,8 @@ breakBlock uniques (BasicBlock ident stmts) entry = breakBlock' uniques current_id entry exits accum_stmts stmts = case stmts of [] -> panic "block doesn't end in jump, goto, return or switch" + + -- Last statement. Make the 'BrokenBlock' [CmmJump target arguments] -> [BrokenBlock current_id entry accum_stmts exits @@ -126,6 +133,9 @@ breakBlock uniques (BasicBlock ident stmts) entry = [BrokenBlock current_id entry accum_stmts (mapMaybe id targets ++ exits) (FinalSwitch expr targets)] + + -- These shouldn't happen in the middle of a block. + -- They would cause dead code. (CmmJump _ _:_) -> panic "jump in middle of block" (CmmReturn _:_) -> panic "return in middle of block" (CmmBranch _:_) -> panic "branch in middle of block" @@ -140,6 +150,8 @@ breakBlock uniques (BasicBlock ident stmts) entry = block = do_call current_id entry accum_stmts exits next_id target results arguments -} + + -- Break the block on safe calls (the main job of this function) (CmmCall target results arguments (CmmSafe srt):stmts) -> block : rest where @@ -149,6 +161,9 @@ breakBlock uniques (BasicBlock ident stmts) entry = rest = breakBlock' (tail uniques) next_id (ContinuationEntry (map fst results) srt) [] [] stmts + + -- Default case. Just keep accumulating statements + -- and branch targets. (s:stmts) -> breakBlock' uniques current_id entry (cond_branch_target s++exits) |