Changeset 251533 in webkit for trunk/Source/JavaScriptCore/offlineasm/mips.rb

Timestamp:

Oct 24, 2019, 1:36:00 AM (6 years ago)

Author:

[email protected]

Message:

Disable pichdr generation on MIPS for return location labels
​https://bugs.webkit.org/show_bug.cgi?id=203040

Patch by Paulo Matos <Paulo Matos> on 2019-10-24
Reviewed by Yusuke Suzuki.

Disable generation of pichdr for return location labels generated in
defineOSRExitReturnLabel. Since r250806 (Allow OSR exit to the LLInt),
MIPS was segfaulting since the pichdr after an OSR exit was corruption
the gp register.

• offlineasm/mips.rb:

File:

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

trunk/Source/JavaScriptCore/offlineasm/mips.rb

@@ -680 +680 @@
         | node |
         myList << node
-        if node.is_a? Label
+        if node.is_a? Label and node.name !~ /^.*_return_location(?:_(?:wide16|wide32))?$/
+            # Only generate a pichdr if the label is not a return location (OSR Exit) - a cpload 
+            # (generated by pichdr) after this type of label would cause the a gp register
+            # corruption. The cpload only sets gp correctly if t9 contains the address of the start
+            # of cpload, which is only the case when we do a `jr t9` (on a OSR Exit).
+            # This regular expression needs to stay in sync with the labels
+            # generated in macro defineOSRExitReturnLabel defined llint/LowLevelInterpreter.asm 
             myList << Instruction.new(node.codeOrigin, "pichdr", [])
         end