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| author | Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com> | 2026-09-26 06:35:22 +0800 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2026-09-25 15:35:22 -0700 |
| commit | dd907c2d86eaaad0910e7bfe3f0d25e5caf8bdf7 (patch) | |
| tree | 8b71264016c53914912e1cd30527b1bf86ed9bf3 /chapter04/README.md | |
| parent | e922879e9dfa402934e2b5860900661b1169492c (diff) | |
| download | Simple-dd907c2d86eaaad0910e7bfe3f0d25e5caf8bdf7.tar.gz Simple-dd907c2d86eaaad0910e7bfe3f0d25e5caf8bdf7.zip | |
Extend and backport SubNode peephole (#254)
* Extend and backport SubNode peephole
* Add tests
* Restrict subtraction zero peepholes to integer operands
Require resolved integer mode in chapter 25 so zero subtraction preserves floating-point signed zero. Keep nonnumeric operands in the graph for subtraction diagnostics.
Add signed-zero coverage from chapter 12 and null-subtraction diagnostics from chapter 22. Confirmed the regressions fail on the original PR. Full Make suites pass in chapters 4-25 (5462 tests), including fresh chapter 25 sys.o compilation.
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Co-authored-by: Cliff Click <cliffc@acm.org>
Diffstat (limited to 'chapter04/README.md')
| -rw-r--r-- | chapter04/README.md | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/chapter04/README.md b/chapter04/README.md index 2c7f7e9c..07085e80 100644 --- a/chapter04/README.md +++ b/chapter04/README.md @@ -305,6 +305,7 @@ Here is a list of peepholes introduced in this Chapter, more will be introduced | Before | After | Description | |-----------------------|-----------------------|------------------------------------------------| | (arg + 0 ) | arg | Add of zero identity | +| (arg - 0 ) | arg | Sub of zero identity | | (arg * 1 ) | arg | Multiple of one identity | | (con + arg) | (arg + con) | Move constants to right, to encourage folding | | (con * arg) | (arg * con) | Move constants to right, to encourage folding | @@ -312,6 +313,9 @@ Here is a list of peepholes introduced in this Chapter, more will be introduced | ((arg1 + con) + arg2) | ((arg1 + arg2) + con) | Move constants to right, to encourage folding | | (arg + arg) | (arg * 2) | Sum-of-products form | | (arg - arg) | 0 | Sub of same is 0 +| (0 - arg) | (-arg) | Sub from 0 is negation +| (arg1 - (-arg2)) | (arg1 + arg2) | Sub of negation is add +| ((-arg1) - arg2) | -(arg1 + arg2) | Sub from negation is negation of sum | (con / 1) | con | Division by one | (arg == arg) | 1 | Compare of same | (arg != arg) | 0 | Compare of same |