8000 Merge pull request #198 from Shopify/noah_asm_comments · kddnewton/ruby@cd6aa4b · GitHub
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Merge pull request ruby#198 from Shopify/noah_asm_comments
Assembly comments on CodeBlocks
2 parents 3d9fab3 + 126f549 commit cd6aa4b

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3 files changed

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-17
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3 files changed

+51
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‎yjit/src/asm/mod.rs

Lines changed: 33 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -87,6 +87,9 @@ pub struct CodeBlock
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// References to labels
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label_refs: Vec<LabelRef>,
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// Comments for assembly instructions, if that feature is enabled
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asm_comments: Vec<(usize, String)>,
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// Keep track of the current aligned write position.
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// Used for changing protection when writing to the JIT buffer
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current_aligned_write_pos: usize,
@@ -116,6 +119,7 @@ impl CodeBlock
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label_addrs: Vec::new(),
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label_names: Vec::new(),
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label_refs: Vec::new(),
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asm_comments: Vec::new(),
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current_aligned_write_pos: ALIGNED_WRITE_POSITION_NONE,
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page_size: 4096,
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dropped_bytes: false
@@ -131,6 +135,7 @@ impl CodeBlock
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label_addrs: Vec::new(),
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label_names: Vec::new(),
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label_refs: Vec::new(),
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asm_comments: Vec::new(),
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current_aligned_write_pos: ALIGNED_WRITE_POSITION_NONE,
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page_size,
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dropped_bytes: false
@@ -142,6 +147,34 @@ impl CodeBlock
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self.write_pos + num_bytes < self.mem_size
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}
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/// Add an assembly comment if the feature is on.
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/// If not, this becomes an inline no-op.
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#[inline]
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pub fn add_comment(&mut self, comment: &str) {
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#[cfg(feature="asm_comments")]
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{
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let is_dup = if let Some((last_pos, last_comment)) = self.asm_comments.last() {
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*last_pos == self.write_pos && *last_comment == comment
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} else { false };
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if !is_dup {
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self.asm_comments.push((self.write_pos, String::from(comment)));
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}
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}
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}
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/// Add an assembly comment at a specific byte offset if the feature is on.
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/// If not, this becomes an inline no-op.
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#[inline]
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pub fn add_comment_at(&mut self, pos:usize, comment: &str) {
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#[cfg(feature="asm_comments")]
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self.asm_comments.push((pos, String::from(comment)));
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}
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/// Get a slice (readonly ref) of assembly comments - if the feature is off, this will be empty.
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pub fn get_comments(&self) -> &[(usize, String)] {
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return self.asm_comments.as_slice();
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}
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pub fn get_write_pos(&self) -> usize {
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self.write_pos
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}

‎yjit/src/asm/x86_64/tests.rs

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -420,3 +420,20 @@ fn basic_capstone_usage() -> std::result::Result<(), capstone::Error> {
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)),
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}
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}
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#[test]
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#[cfg(feature = "asm_comments")]
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fn block_comments() {
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let mut cb = super::CodeBlock::new_dummy(4096);
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cb.add_comment("Beginning");
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xor(&mut cb, EAX, EAX); // 2 bytes long
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cb.add_comment("Two bytes in");
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cb.add_comment("Two bytes in"); // Duplicate, should be ignored
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test(&mut cb, mem_opnd(64, RSI, 64), imm_opnd(!0x08)); // 8 bytes long
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cb.add_comment("Ten bytes in");
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let comments = cb.get_comments();
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let expected:Vec<(usize,String)> = vec!( (0, "Beginning".to_string()), (2, "Two bytes in".to_string()), (10, "Ten bytes in".to_string()) );
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assert_eq!(expected, comments);
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}

‎yjit/src/codegen.rs

Lines changed: 1 addition & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -239,23 +239,7 @@ fn add_comment(cb: &mut CodeBlock, comment_str: &str)
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{
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#[cfg(feature = "asm_comments")]
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{
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/*
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// We can't add comments to the outlined code block
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if (cb == ocb)
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return;
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// Avoid adding duplicate comment strings (can happen due to deferred codegen)
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size_t num_comments = rb_darray_size(yjit_code_comments);
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if (num_comments > 0) {
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struct yjit_comment last_comment = rb_darray_get(yjit_code_comments, num_comments - 1);
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if (last_comment.offset == cb->write_pos && strcmp(last_comment.comment, comment_str) == 0) {
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return;
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}
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}
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struct yjit_comment new_comment = (struct yjit_comment){ cb->write_pos, comment_str };
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rb_darray_append(&yjit_code_comments, new_comment);
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*/
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cb.add_comment(comment_str);
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}
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}
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