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8371458: [REDO] Remove exception handler stub code in C2 #28192

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8371458: [REDO] Remove exception handler stub code in C2 #28192

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441008a
8365047: Remove exception handler stub code in C2
ruben-arm May 14, 2025
2d8012a
Address review comments
ruben-arm Aug 14, 2025
1f6546e
Ensure stub code is not adjacent to a call
ruben-arm May 14, 2025
7d1ece5
Revert "Ensure stub code is not adjacent to a call"
ruben-arm Sep 12, 2025
4717824
Offset the deoptimization handler entry point
ruben-arm Sep 12, 2025
fe7db04
The patch is contributed by @TheRealMDoerr
ruben-arm Sep 26, 2025
5107d02
Address review comments
ruben-arm Sep 26, 2025
18e36ec
Address review comments
ruben-arm Sep 29, 2025
6e24110
Address review comments
ruben-arm Oct 13, 2025
60279c3
Merge from the main branch
ruben-arm Oct 13, 2025
e9c817c
Test for deoptimization in virtual threads
ruben-arm Oct 28, 2025
de9bec5
Check for NOP and MOVK separately in NativePostCallNop
ruben-arm Oct 28, 2025
462dbf6
Address review comments and fix a mistype
ruben-arm Oct 28, 2025
dc32139
Merge from the main branch
ruben-arm Nov 3, 2025
359c2f1
Rename deoptHandlerOffsetField -> deoptHandlerEntryOffsetField
ruben-arm Nov 3, 2025
7bb4352
x86: Fix post-call NOP check access outside code blob
ruben-arm Nov 7, 2025
20cc58a
Add an assertion to detect out of bounds access in post-call NOP checks
ruben-arm Nov 13, 2025
3a01437
Replace `guarantee` with `assert` in the C1 `emit_deopt_handler`
ruben-arm Nov 18, 2025
00ea0e1
Refine `first_check_size` definitions
ruben-arm Nov 20, 2025
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2 changes: 1 addition & 1 deletion src/hotspot/cpu/x86/c1_LIRAssembler_x86.hpp
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Expand Up @@ -48,7 +48,7 @@
enum {
_call_stub_size = 28,
_exception_handler_size = DEBUG_ONLY(1*K) NOT_DEBUG(175),
_deopt_handler_size = 10
_deopt_handler_size = 7
};

public:
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3 changes: 2 additions & 1 deletion src/hotspot/cpu/x86/nativeInst_x86.hpp
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Expand Up @@ -73,6 +73,7 @@ class NativeInstruction {
s_char sbyte_at(int offset) const { return *(s_char*) addr_at(offset); }
u_char ubyte_at(int offset) const { return *(u_char*) addr_at(offset); }

jshort short_at(int offset) const { return *(jshort*) addr_at(offset); }
jint int_at(int offset) const { return *(jint*) addr_at(offset); }

intptr_t ptr_at(int offset) const { return *(intptr_t*) addr_at(offset); }
Expand Down Expand Up @@ -581,7 +582,7 @@ class NativePostCallNop: public NativeInstruction {
displacement_offset = 4
};

bool check() const { return int_at(0) == 0x841f0f; }
bool check() const { return short_at(0) == 0x1f0f && short_at(2) == 0x0084; }
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@TheRealMDoerr TheRealMDoerr Nov 10, 2025

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Maybe a comment would be nice.

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@ruben-arm ruben-arm Nov 13, 2025

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Thanks for the suggestion. Would the comments added at 20cc58a be suitable?

bool decode(int32_t& oopmap_slot, int32_t& cb_offset) const {
int32_t data = int_at(displacement_offset);
if (data == 0) {
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2 changes: 1 addition & 1 deletion src/hotspot/cpu/x86/x86.ad
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Expand Up @@ -2771,7 +2771,7 @@ class HandlerImpl {

static uint size_deopt_handler() {
// one call and one jmp.
return 10;
return 7;
}
};

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