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9686e666ef
This patch aims to provide correct dwarf unwind information in function epilogue for X86. It consists of two parts. The first part inserts CFI instructions that set appropriate cfa offset and cfa register in emitEpilogue() in X86FrameLowering. This part is X86 specific. The second part is platform independent and ensures that: * CFI instructions do not affect code generation (they are not counted as instructions when tail duplicating or tail merging) * Unwind information remains correct when a function is modified by different passes. This is done in a late pass by analyzing information about cfa offset and cfa register in BBs and inserting additional CFI directives where necessary. Added CFIInstrInserter pass: * analyzes each basic block to determine cfa offset and register are valid at its entry and exit * verifies that outgoing cfa offset and register of predecessor blocks match incoming values of their successors * inserts additional CFI directives at basic block beginning to correct the rule for calculating CFA Having CFI instructions in function epilogue can cause incorrect CFA calculation rule for some basic blocks. This can happen if, due to basic block reordering, or the existence of multiple epilogue blocks, some of the blocks have wrong cfa offset and register values set by the epilogue block above them. CFIInstrInserter is currently run only on X86, but can be used by any target that implements support for adding CFI instructions in epilogue. Patch by Violeta Vukobrat. Differential Revision: https://reviews.llvm.org/D42848 llvm-svn: 330706
86 lines
2.6 KiB
LLVM
86 lines
2.6 KiB
LLVM
; RUN: llc %s -o - | FileCheck %s
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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$__clang_call_terminate = comdat any
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@_ZL11ShouldThrow = internal unnamed_addr global i1 false, align 1
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@_ZTIi = external constant i8*
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@str = private unnamed_addr constant [20 x i8] c"Threw an exception!\00"
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; Function Attrs: uwtable
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define void @_Z6throwsv() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
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; CHECK-LABEL: _Z6throwsv:
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; CHECK: popq %rbx
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; CHECK-NEXT: .cfi_def_cfa_offset 8
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; CHECK-NEXT: retq
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; CHECK-NEXT: .LBB0_1:
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; CHECK-NEXT: .cfi_def_cfa_offset 16
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entry:
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%.b5 = load i1, i1* @_ZL11ShouldThrow, align 1
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br i1 %.b5, label %if.then, label %try.cont
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if.then: ; preds = %entry
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%exception = tail call i8* @__cxa_allocate_exception(i64 4)
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%0 = bitcast i8* %exception to i32*
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store i32 1, i32* %0, align 16
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invoke void @__cxa_throw(i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null)
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to label %unreachable unwind label %lpad
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lpad: ; preds = %if.then
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%1 = landingpad { i8*, i32 }
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catch i8* null
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%2 = extractvalue { i8*, i32 } %1, 0
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%3 = tail call i8* @__cxa_begin_catch(i8* %2)
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%puts = tail call i32 @puts(i8* getelementptr inbounds ([20 x i8], [20 x i8]* @str, i64 0, i64 0))
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invoke void @__cxa_rethrow() #4
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to label %unreachable unwind label %lpad1
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lpad1: ; preds = %lpad
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%4 = landingpad { i8*, i32 }
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cleanup
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invoke void @__cxa_end_catch()
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to label %eh.resume unwind label %terminate.lpad
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try.cont: ; preds = %entry
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ret void
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eh.resume: ; preds = %lpad1
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resume { i8*, i32 } %4
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terminate.lpad: ; preds = %lpad1
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%5 = landingpad { i8*, i32 }
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catch i8* null
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%6 = extractvalue { i8*, i32 } %5, 0
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tail call void @__clang_call_terminate(i8* %6)
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unreachable
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unreachable: ; preds = %lpad, %if.then
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unreachable
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}
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declare i8* @__cxa_allocate_exception(i64)
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declare void @__cxa_throw(i8*, i8*, i8*)
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declare i32 @__gxx_personality_v0(...)
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declare i8* @__cxa_begin_catch(i8*)
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declare void @__cxa_rethrow()
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declare void @__cxa_end_catch()
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; Function Attrs: noinline noreturn nounwind
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declare void @__clang_call_terminate(i8*)
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declare void @_ZSt9terminatev()
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; Function Attrs: nounwind
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declare i32 @puts(i8* nocapture readonly)
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