mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-11-01 15:11:24 +00:00
472f2a056d
As with x86 and AArch64, certain situations can arise where we need to spill CPSR in the middle of a calculation. These should be avoided where possible (MRS/MSR is rather expensive), which ARM is actually better at than the other two since it tries to Glue defs to uses, but as a last ditch effort, copying is better than crashing. rdar://problem/18011155 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218789 91177308-0d34-0410-b5e6-96231b3b80d8
42 lines
1.8 KiB
LLVM
42 lines
1.8 KiB
LLVM
; RUN: llc -mtriple=armv7s-apple-ios7.0 -show-mc-encoding %s -o - | FileCheck %s --check-prefix=CHECK-ARM
|
|
; RUN: llc -mtriple=thumbv7s-apple-ios7.0 -show-mc-encoding %s -o - | FileCheck %s --check-prefix=CHECK-THUMB
|
|
; RUN: llc -mtriple=thumbv7m-none-eabi -show-mc-encoding %s -o - | FileCheck %s --check-prefix=CHECK-THUMB
|
|
|
|
; In the ARM backend, most compares are glued to their uses so CPSR can't
|
|
; escape. However, for long ADCS chains (and last ditch fallback) the dependency
|
|
; is carried in the DAG because duplicating them can be more expensive than
|
|
; copying CPSR.
|
|
|
|
; Crafting a test for this was a little tricky, in case it breaks here are some
|
|
; notes on what I was tring to achieve:
|
|
; + We want 2 long ADCS chains
|
|
; + We want them to split after an initial common prefix (so that a single
|
|
; CPSR is used twice).
|
|
; + We want both chains to write CPSR post-split (so that the copy can't be
|
|
; elided).
|
|
; + We want the chains to be long enough that duplicating them is expensive.
|
|
|
|
define void @test_copy_cpsr(i128 %lhs, i128 %rhs, i128* %addr) {
|
|
; CHECK-ARM: test_copy_cpsr:
|
|
; CHECK-THUMB: test_copy_cpsr:
|
|
|
|
; CHECK-ARM: mrs [[TMP:r[0-9]+]], apsr @ encoding: [0x00,0x{{[0-9a-f]}}0,0x0f,0xe1]
|
|
; CHECK-ARM: msr APSR_nzcvq, [[TMP]] @ encoding: [0x0{{[0-9a-f]}},0xf0,0x28,0xe1]
|
|
|
|
; In Thumb mode v7M and v7AR have different MRS/MSR instructions that happen
|
|
; to overlap for the apsr case, so it's definitely worth checking both.
|
|
; CHECK-THUMB: mrs [[TMP:r[0-9]+]], apsr @ encoding: [0xef,0xf3,0x00,0x8{{[0-9a-f]}}]
|
|
; CHECK-THUMB: msr {{APSR|apsr}}_nzcvq, [[TMP]] @ encoding: [0x8{{[0-9a-f]}},0xf3,0x00,0x88]
|
|
|
|
%sum = add i128 %lhs, %rhs
|
|
store volatile i128 %sum, i128* %addr
|
|
|
|
%rhs2.tmp1 = trunc i128 %rhs to i64
|
|
%rhs2 = zext i64 %rhs2.tmp1 to i128
|
|
|
|
%sum2 = add i128 %lhs, %rhs2
|
|
store volatile i128 %sum2, i128* %addr
|
|
|
|
ret void
|
|
}
|