Change stackwalking to always use unadjusted IP

Handling of hardware exceptions had a hack to add +1 to the actual instruction IP. Windows x64 unwinder
is disassembling instructions at the IP passed in to detect method epilogs. If the bytes at IP + 1
happened to match the epilog pattern, the unwind is done as if we were in the middle of the epilog that
lead to spectacular crash.

This change is moving this adjustment to be done later for EH related things only, and not interfere
with stackwalking.

Fixes #2535

[tfs-changeset: 1645602]

1 files changed, 0 insertions, 9 deletions

diff --git a/src/Native/Runtime/i386/ExceptionHandling.asm b/src/Native/Runtime/i386/ExceptionHandling.asm
index 0d0fd7d04..d96ed44b8 100644
--- a/src/Native/Runtime/i386/ExceptionHandling.asm
+++ b/src/Native/Runtime/i386/ExceptionHandling.asm
@@ -29,15 +29,6 @@ FASTCALL_FUNC  RhpThrowHwEx, 0
         esp_offsetof_ExInfo     textequ %0
         esp_offsetof_Context    textequ %SIZEOF__ExInfo
 
-
-        add     edx, 1  ;; 'faulting IP' += 1, we do this because everywhere else we treat the faulting IP as
-                        ;; a return-address and optionally subtract one when doing EH-related things (but not
-                        ;; subtracting 1 when doing GC-related things).  The fault IP here will be the start
-                        ;; of the faulting instruction, so +1 will point to either the next instruction or the
-                        ;; middle of this instruction.  Either way, when the dispatch / stackwalk code deals
-                        ;; with this address it'll apply a -1 for EH range checks and the GC-related operations
-                        ;; don't need to be precise here because the fault location isn't a GC safe point 
-
         push    edx         ; make it look like we were called by pushing the faulting IP like a return address
         push    ebp
         mov     ebp, esp