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llvm-mirror/test/CodeGen/X86/win64-jumptable.ll
Hans Wennborg 0be5551915 Revert "[CodeGen] [WinException] Only produce handler data at the end of the function if needed"
This caused an explosion in ICF times during linking on Windows when libfuzzer
instrumentation is enabled. For a small binary we see ICF time go from ~0 to
~10 s. For a large binary it goes from ~1 s to forevert (I gave up after 30
minutes).

See comment on the code review.

> If we are going to write handler data (that is written as variable
> length data following after the unwind info in .xdata), we need to
> emit the handler data immediately, but for cases where no such
> info is going to be written, skip emitting it right away. (Unwind
> info for all remaining functions that hasn't gotten it emitted
> directly is emitted at the end.)
>
> This does slightly change the ordering of sections (triggering a
> bunch of updates to DebugInfo/COFF tests), but the change should be
> benign.
>
> This also matches GCC's assembly output, which doesn't output
> .seh_handlerdata unless it actually is needed.
>
> For ARM64, the unwind info can be packed into the runtime function
> entry itself (leaving no data in the .xdata section at all), but
> that can only be done if there's no follow-on data in the .xdata
> section. If emission of the unwind info is triggered via
> EmitWinEHHandlerData (or the .seh_handlerdata directive), which
> implicitly switches to the .xdata section, there's a chance of the
> caller wanting to pass further data there, so the packed format
> can't be used in that case.
>
> Differential Revision: https://reviews.llvm.org/D87448

This reverts commit 36c64af9d7f97414d48681b74352c9684077259b.
2020-11-03 13:12:10 +01:00

61 lines
1.6 KiB
LLVM

; RUN: llc < %s -relocation-model static | FileCheck %s
; FIXME: Remove '-relocation-model static' when it is no longer necessary to
; trigger the separate .rdata section.
target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc19.0.24215"
define void @f(i32 %x) {
entry:
switch i32 %x, label %sw.epilog [
i32 0, label %sw.bb
i32 1, label %sw.bb1
i32 2, label %sw.bb2
i32 3, label %sw.bb3
]
sw.bb: ; preds = %entry
tail call void @g(i32 0) #2
br label %sw.epilog
sw.bb1: ; preds = %entry
tail call void @g(i32 1) #2
br label %sw.epilog
sw.bb2: ; preds = %entry
tail call void @g(i32 2) #2
br label %sw.epilog
sw.bb3: ; preds = %entry
tail call void @g(i32 3) #2
br label %sw.epilog
sw.epilog: ; preds = %entry, %sw.bb3, %sw.bb2, %sw.bb1, %sw.bb
tail call void @g(i32 10) #2
ret void
}
declare void @g(i32)
; CHECK: .text
; CHECK: f:
; CHECK: .seh_proc f
; CHECK: jmpq *.LJTI0_0
; CHECK: .LBB0_{{.*}}: # %sw.bb
; CHECK: .LBB0_{{.*}}: # %sw.bb1
; CHECK: .LBB0_{{.*}}: # %sw.bb2
; CHECK: .LBB0_{{.*}}: # %sw.bb3
; CHECK: callq g
; CHECK: jmp g # TAILCALL
; CHECK: .section .rdata,"dr"
; CHECK: .quad .LBB0_
; CHECK: .quad .LBB0_
; CHECK: .quad .LBB0_
; CHECK: .quad .LBB0_
; CHECK: .seh_handlerdata
; It's important that we switch back to .text here, not .rdata.
; CHECK: .text
; CHECK: .seh_endproc