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llvm-mirror/test/CodeGen/X86/retpoline-regparm.ll
Reid Kleckner f0fe7234f4 [X86] Use EDI for retpoline when no scratch regs are left
Summary:
Instead of solving the hard problem of how to pass the callee to the indirect
jump thunk without a register, just use a CSR. At a call boundary, there's
nothing stopping us from using a CSR to hold the callee as long as we save and
restore it in the prologue.

Also, add tests for this mregparm=3 case. I wrote execution tests for
__llvm_retpoline_push, but they never got committed as lit tests, either
because I never rewrote them or because they got lost in merge conflicts.

Reviewers: chandlerc, dwmw2

Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D43214

llvm-svn: 325049
2018-02-13 20:47:49 +00:00

43 lines
1.2 KiB
LLVM

; RUN: llc -mtriple=i686-linux < %s | FileCheck --implicit-check-not="jmp.*\*" --implicit-check-not="call.*\*" %s
; Test 32-bit retpoline when -mregparm=3 is used. This case is interesting
; because there are no available scratch registers. The Linux kernel builds
; with -mregparm=3, so we need to support it. TCO should fail because we need
; to restore EDI.
define void @call_edi(void (i32, i32, i32)* %fp) #0 {
entry:
tail call void %fp(i32 inreg 0, i32 inreg 0, i32 inreg 0)
ret void
}
; CHECK-LABEL: call_edi:
; EDI is used, so it must be saved.
; CHECK: pushl %edi
; CHECK-DAG: xorl %eax, %eax
; CHECK-DAG: xorl %edx, %edx
; CHECK-DAG: xorl %ecx, %ecx
; CHECK-DAG: movl {{.*}}, %edi
; CHECK: calll __llvm_retpoline_edi
; CHECK: popl %edi
; CHECK: retl
define void @edi_external(void (i32, i32, i32)* %fp) #1 {
entry:
tail call void %fp(i32 inreg 0, i32 inreg 0, i32 inreg 0)
ret void
}
; CHECK-LABEL: edi_external:
; CHECK: pushl %edi
; CHECK-DAG: xorl %eax, %eax
; CHECK-DAG: xorl %edx, %edx
; CHECK-DAG: xorl %ecx, %ecx
; CHECK-DAG: movl {{.*}}, %edi
; CHECK: calll __x86_indirect_thunk_edi
; CHECK: popl %edi
; CHECK: retl
attributes #0 = { "target-features"="+retpoline" }
attributes #1 = { "target-features"="+retpoline-external-thunk" }