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llvm-project/llvm/test/CodeGen/X86/eh-unknown.ll

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[EH] Fix the LSDA that we emit for unknown EH personalities We should have a single call site entry with no landing pad. This indicates that no EH action should be taken and the unwinder should unwind to the next frame. We currently don't recognize __gxx_personality_seh0 as a known personality, so we forcibly emit a table, and that table was wrong. This was filed as PR33220. Now we emit a correct table for that personality. The next step is to recognize that we can completely skip the table for this personality. llvm-svn: 304363
2017-06-01 06:18:49 +08:00
; RUN: llc -mtriple=x86_64-windows-msvc < %s | FileCheck %s
; An unknown personality forces us to emit an Itanium LSDA. Make sure that the
; Itanium call site table actually tells the personality to keep unwinding,
; i.e. we have an entry and it says "has no landing pad".
declare void @throwit()
declare void @__unknown_ehpersonality(...)
define void @use_unknown_ehpersonality()
personality void (...)* @__unknown_ehpersonality {
entry:
call void @throwit()
unreachable
}
; CHECK-LABEL: use_unknown_ehpersonality:
; CHECK: .Lfunc_begin0:
; CHECK: .seh_handler __unknown_ehpersonality, @unwind, @except
; CHECK: callq throwit
; CHECK: .Lfunc_end0:
; CHECK: .seh_handlerdata
; CHECK: .Lexception0:
; CHECK: .byte 255 # @LPStart Encoding = omit
Emit smaller exception tables for non-SJLJ mode. * Use uleb128 for code offsets in the LSDA call site table. * Omit the TTBase offset if the type table is empty. This change can reduce the size of the DWARF/Itanium LSDA by about half. Patch by Ryan Prichard! llvm-svn: 324750
2018-02-10 01:13:37 +08:00
; CHECK: .byte 255 # @TType Encoding = omit
; CHECK: .byte 1 # Call site Encoding = uleb128
Use assembler expressions to lay out the EH LSDA. Rely on the assembler to finalize the layout of the DWARF/Itanium exception-handling LSDA. Rather than calculate the exact size of each thing in the LSDA, use assembler directives: To emit the offset to the TTBase label: .uleb128 .Lttbase0-.Lttbaseref0 .Lttbaseref0: To emit the size of the call site table: .uleb128 .Lcst_end0-.Lcst_begin0 .Lcst_begin0: ... call site table entries ... .Lcst_end0: To align the type info table: ... action table ... .balign 4 .long _ZTIi .long _ZTIl .Lttbase0: Using assembler directives simplifies the compiler and allows switching the encoding of offsets in the call site table from udata4 to uleb128 for a large code size savings. (This commit does not change the encoding.) The combination of the uleb128 followed by a balign creates an unfortunate dependency cycle that the assembler must sometimes resolve either by padding an LEB or by inserting zero padding before the type table. See PR35809 or GNU as bug 4029. Patch by Ryan Prichard! llvm-svn: 324749
2018-02-10 01:00:25 +08:00
; CHECK: .uleb128 .Lcst_end0-.Lcst_begin0
; CHECK: .Lcst_begin0:
Emit smaller exception tables for non-SJLJ mode. * Use uleb128 for code offsets in the LSDA call site table. * Omit the TTBase offset if the type table is empty. This change can reduce the size of the DWARF/Itanium LSDA by about half. Patch by Ryan Prichard! llvm-svn: 324750
2018-02-10 01:13:37 +08:00
; CHECK: .uleb128 .Lfunc_begin0-.Lfunc_begin0 # >> Call Site 1 <<
; CHECK: .uleb128 .Lfunc_end0-.Lfunc_begin0 # Call between .Lfunc_begin0 and .Lfunc_end0
; CHECK: .byte 0 # has no landing pad
[EH] Fix the LSDA that we emit for unknown EH personalities We should have a single call site entry with no landing pad. This indicates that no EH action should be taken and the unwinder should unwind to the next frame. We currently don't recognize __gxx_personality_seh0 as a known personality, so we forcibly emit a table, and that table was wrong. This was filed as PR33220. Now we emit a correct table for that personality. The next step is to recognize that we can completely skip the table for this personality. llvm-svn: 304363
2017-06-01 06:18:49 +08:00
; CHECK: .byte 0 # On action: cleanup
Use assembler expressions to lay out the EH LSDA. Rely on the assembler to finalize the layout of the DWARF/Itanium exception-handling LSDA. Rather than calculate the exact size of each thing in the LSDA, use assembler directives: To emit the offset to the TTBase label: .uleb128 .Lttbase0-.Lttbaseref0 .Lttbaseref0: To emit the size of the call site table: .uleb128 .Lcst_end0-.Lcst_begin0 .Lcst_begin0: ... call site table entries ... .Lcst_end0: To align the type info table: ... action table ... .balign 4 .long _ZTIi .long _ZTIl .Lttbase0: Using assembler directives simplifies the compiler and allows switching the encoding of offsets in the call site table from udata4 to uleb128 for a large code size savings. (This commit does not change the encoding.) The combination of the uleb128 followed by a balign creates an unfortunate dependency cycle that the assembler must sometimes resolve either by padding an LEB or by inserting zero padding before the type table. See PR35809 or GNU as bug 4029. Patch by Ryan Prichard! llvm-svn: 324749
2018-02-10 01:00:25 +08:00
; CHECK: .Lcst_end0: