Changeset 281321 in webkit for trunk/Source/JavaScriptCore/offlineasm/ast.rb

Timestamp:

Aug 20, 2021, 10:01:00 AM (4 years ago)

Author:

[email protected]

Message:

Add some offlineasm enhancements.
​https://bugs.webkit.org/show_bug.cgi?id=229332
rdar://82163923

Reviewed by Keith Miller.

1. Enhance "include" offlineasm Instruction to always attempt to include an asm file from <build-products>/usr/local/include/WebKitAdditions/ first. If the specified file is not available there, then it will attempt to include the file from the same directory as the current source file (which in practice, means Source/JavaScriptCore/llint/).

2. Enhance "include" offlineasm Instruction to allow an optional file to be included if it exists. For example, the following offlineasm code:

include? LowLevelInterpreterAdditions

... will attempt to include a file LowLevelInterpreterAdditions.asm. If the
file does not exist, this will be a no-op. Note: the "?" after the "include"
means the include is optional.

3. Enhanced "emit" offlineasm Instruction to be able to take more than one operand.

"emit" used to just copy the string operand that follows into the generated
LLIntAssembly.h. Now, "emit" can take multiple comma separated operands, and
will concatenate all the operands.

Additionally, "emit" can now take a LocalLabelReference as an operand. For
example, this offline asm code:

emit "b ", .done
...

.done:

... will generate this inline asm code in LLIntAssembly.h:

"b " LOCAL_LABEL_STRING(_offlineasm_someLabel_done) "\n"

This makes it easier to emit branches to local labels.

4. Also fixed LLInt code alignment for ARM_THUMB2 and ARM64.

Previously, it was aligned using ".align 4" which means aligned on a 4
instruction boundary. Note: the interpretation of .align varies for different
target CPU architectures.

Now, we do the alignment using ".balign 4" which means align on a 4 byte
boundary. This is the intended alignment because ARM64 instruction size is
4 bytes, and ARM_THUMB2 instruction size is either 2 bytes or 4 bytes.
Using .align before was potentially wasting some code space.

• llint/LowLevelInterpreter.asm:
• llint/LowLevelInterpreter.cpp:
• offlineasm/ast.rb:
• offlineasm/parser.rb:

File:

• trunk/Source/JavaScriptCore/offlineasm/ast.rb (modified) (1 diff)

trunk/Source/JavaScriptCore/offlineasm/ast.rb

@@ -945 +945 @@
             $asm.putGlobalAnnotation
         when "emit"
-            $asm.puts "#{operands[0].dump}"
+            str = "";
+            for operand in operands do
+                if (operand.is_a? LocalLabelReference)
+                    str += operand.asmLabel
+                else
+                    str += "#{operand.dump}"
+                end
+            end
+            $asm.puts "#{str}"
         when "tagCodePtr", "tagReturnAddress", "untagReturnAddress", "removeCodePtrTag", "untagArrayPtr", "removeArrayPtrTag"
         else