4c89277095
D52985/D57677 added a .gcc_except_table workaround, but the new behavior
doesn't match GNU assembler.
```
void foo();
int bar() {
foo();
try { throw 1; }
catch (int) { return 1; }
return 0;
}
clang --target=mipsel-linux-gnu -mmicromips -S a.cc
mipsel-linux-gnu-gcc -mmicromips -c a.s -o gnu.o
.uleb128 ($cst_end0)-($cst_begin0) // bit 0 is not forced to 1
.uleb128 ($func_begin0)-($func_begin0) // bit 0 is not forced to 1
```
I have inspected `.gcc_except_table` output by `mipsel-linux-gnu-gcc -mmicromips -c a.cc`.
The `.uleb128` values are not forced to set the least significant bit.
In addition, D57677's adjustment (even->odd) to CodeGen/Mips/micromips-b-range.ll is wrong.
PC-relative `.long func - .` values will differ from GNU assembler as well.
The original intention of D52985 seems unclear to me. I think whatever
goal it wants to achieve should be moved to an upper layer.
This isMicroMips special case has caused problems to fix MCAssembler::relaxLEB to use evaluateAsAbsolute instead of evaluateKnownAbsolute,
which is needed to proper support R_RISCV_SET_ULEB128/R_RISCV_SUB_ULEB128.
Differential Revision: https://reviews.llvm.org/D157655
37 lines
1.1 KiB
LLVM
37 lines
1.1 KiB
LLVM
; RUN: llc -mtriple=mips-linux-gnu -mcpu=mips32r2 -mattr=+micromips -O3 -filetype=obj < %s | llvm-objdump -s -j .gcc_except_table - | FileCheck %s
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; CHECK: Contents of section .gcc_except_table:
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; CHECK-NEXT: 0000 ff9b1501 0c001000 00100e1e 011e1800
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; CHECK-NEXT: 0010 00010000 00000000
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@_ZTIi = external constant ptr
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define dso_local i32 @main() local_unnamed_addr norecurse personality ptr @__gxx_personality_v0 {
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entry:
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%exception.i = tail call ptr @__cxa_allocate_exception(i32 4) nounwind
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store i32 5, ptr %exception.i, align 16
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invoke void @__cxa_throw(ptr %exception.i, ptr @_ZTIi, ptr null) noreturn
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to label %.noexc unwind label %return
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.noexc:
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unreachable
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return:
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%0 = landingpad { ptr, i32 }
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catch ptr null
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%1 = extractvalue { ptr, i32 } %0, 0
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%2 = tail call ptr @__cxa_begin_catch(ptr %1) nounwind
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tail call void @__cxa_end_catch()
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ret i32 0
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}
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declare i32 @__gxx_personality_v0(...)
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declare ptr @__cxa_begin_catch(ptr) local_unnamed_addr
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declare void @__cxa_end_catch() local_unnamed_addr
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declare ptr @__cxa_allocate_exception(i32) local_unnamed_addr
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declare void @__cxa_throw(ptr, ptr, ptr) local_unnamed_addr
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