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llvm-mirror/test/CodeGen/ARM/jump-table-islands-split.ll
Tim Northover 0eb976c493 ARM: recommit r237590: allow jump tables to be placed as constant islands.
The original version didn't properly account for the base register
being modified before the final jump, so caused miscompilations in
Chromium and LLVM. I've fixed this and tested with an LLVM self-host
(I don't have the means to build & test Chromium).

The general idea remains the same: in pathological cases jump tables
can be too far away from the instructions referencing them (like other
constants) so they need to be movable.

Should fix PR23627.

llvm-svn: 238680
2015-05-31 19:22:07 +00:00

53 lines
1.5 KiB
LLVM

; RUN: llc -mtriple=thumbv7s-apple-ios8.0 -o - %s | FileCheck %s
declare void @foo(double)
declare i32 @llvm.arm.space(i32, i32)
; The constpool entry used to call @foo should be directly between where we want
; the tbb and its table. Fortunately, the flow is simple enough that we can
; eliminate the entry calculation (ADD) and use the ADR as the base.
;
; I'm hoping this won't be fragile, but if it does break the most likely fix is
; adjusting the @llvm.arm.space call slightly. If this happens too many times
; the test should probably be removed.
define i32 @test_jumptable_not_adjacent(i1 %tst, i32 %sw, i32 %l) {
; CHECK-LABEL: test_jumptable_not_adjacent:
; CHECK: vldr {{d[0-9]+}}, [[DBL_CONST:LCPI[0-9]+_[0-9]+]]
; [...]
; CHECK: adr.w r[[BASE:[0-9]+]], [[JUMP_TABLE:LJTI[0-9]+_[0-9]+]]
; CHECK-NOT: r[[BASE]]
; CHECK: [[TBB_KEY:LCPI[0-9]+_[0-9]+]]:
; CHECK-NEXT: tbb [r[[BASE]], {{r[0-9]+}}]
; CHECK: [[DBL_CONST]]:
; CHECK: .long
; CHECK: .long
; CHECK: [[JUMP_TABLE]]:
; CHECK: .byte (LBB{{[0-9]+}}_{{[0-9]+}}-([[TBB_KEY]]+4)
br label %complex
complex:
call void @foo(double 12345.0)
call i32 @llvm.arm.space(i32 970, i32 undef)
switch i32 %sw, label %second [ i32 0, label %other
i32 1, label %third
i32 2, label %end
i32 3, label %other ]
second:
ret i32 43
third:
ret i32 0
other:
call void @bar()
unreachable
end:
ret i32 42
}
declare void @bar()