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llvm-project/llvm/test/CodeGen/X86/base-pointer-and-mwaitx.ll
Pierre Gousseau cda6b09242 [X86] Make sure we do not clobber RBX with mwaitx when used as a base 
pointer.

mwaitx uses EBX as one of its argument.
Using this instruction clobbers RBX as it is defined to hold one of the
input. When the backend uses dynamically allocated stack, RBX is used as
a reserved register for the base pointer.

This patch is adapted from @qcolombet patch for cmpxchg at r263325.

This fixes PR43528.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D73475
2020-08-26 11:20:31 +01:00

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; RUN: llc -mtriple=x86_64-pc-linux-gnu -mattr=+mwaitx -x86-use-base-pointer=true -stackrealign -stack-alignment=32 %s -o - | FileCheck --check-prefix=CHECK --check-prefix=USE_BASE_64 %s
; RUN: llc -mtriple=x86_64-pc-linux-gnux32 -mattr=+mwaitx -x86-use-base-pointer=true -stackrealign -stack-alignment=32 %s -o - | FileCheck --check-prefix=CHECK --check-prefix=USE_BASE_32 %s
; RUN: llc -mtriple=x86_64-pc-linux-gnu -mattr=+mwaitx -x86-use-base-pointer=true %s -o - | FileCheck --check-prefix=CHECK --check-prefix=NO_BASE_64 %s
; RUN: llc -mtriple=x86_64-pc-linux-gnux32 -mattr=+mwaitx -x86-use-base-pointer=true %s -o - | FileCheck --check-prefix=CHECK --check-prefix=NO_BASE_32 %s
; This test checks that we save and restore the base pointer (ebx or rbx) in the
; presence of the mwaitx intrinsic which requires to use ebx for one of its
; argument.
; This function uses a dynamically allocated stack to force the use
; of a base pointer.
; After the call to the mwaitx intrinsic we do a volatile store to the
; dynamically allocated memory which will require the use of the base pointer.
; The base pointer should therefore be restored straight after the mwaitx
; instruction.
define void @test_baseptr(i64 %x, i64 %y, i32 %E, i32 %H, i32 %C) nounwind {
entry:
%ptr = alloca i8*, align 8
%0 = alloca i8, i64 %x, align 16
store i8* %0, i8** %ptr, align 8
call void @llvm.x86.mwaitx(i32 %E, i32 %H, i32 %C)
%1 = load i8*, i8** %ptr, align 8
%arrayidx = getelementptr inbounds i8, i8* %1, i64 %y
store volatile i8 42, i8* %arrayidx, align 1
ret void
}
; CHECK-LABEL: test_baseptr:
; USE_BASE_64: movq %rsp, %rbx
; Pass mwaitx first 2 arguments in eax and ecx respectively.
; USE_BASE_64: movl %ecx, %eax
; USE_BASE_64: movl %edx, %ecx
; Save base pointer.
; USE_BASE_64: movq %rbx, [[SAVE_rbx:%r([8-9]|1[0-5]|di|si)]]
; Set mwaitx ebx argument.
; USE_BASE_64: movl %r8d, %ebx
; USE_BASE_64-NEXT: mwaitx
; Restore base pointer.
; USE_BASE_64-NEXT: movq [[SAVE_rbx]], %rbx
; USE_BASE_32: movl %esp, %ebx
; Pass mwaitx first 2 arguments in eax and ecx respectively.
; USE_BASE_32: movl %ecx, %eax
; USE_BASE_32: movl %edx, %ecx
; Save base pointer.
; USE_BASE_32: movl %ebx, [[SAVE_ebx:%e(di|si)]]
; Set mwaitx ebx argument.
; USE_BASE_32: movl %r8d, %ebx
; USE_BASE_32-NEXT: mwaitx
; Restore base pointer.
; USE_BASE_32-NEXT: movl [[SAVE_ebx]], %ebx
; Pass mwaitx 3 arguments in eax, ecx, ebx
; NO_BASE_64: movl %r8d, %ebx
; NO_BASE_64: movl %ecx, %eax
; NO_BASE_64: movl %edx, %ecx
; No need to save base pointer.
; NO_BASE_64-NOT: movq %rbx
; NO_BASE_64: mwaitx
; No need to restore base pointer.
; NO_BASE_64-NOT: movq {{.*}}, %rbx
; NO_BASE_64-NEXT: {{.+$}}
; Pass mwaitx 3 arguments in eax, ecx, ebx
; NO_BASE_32: movl %r8d, %ebx
; NO_BASE_32: movl %ecx, %eax
; NO_BASE_32: movl %edx, %ecx
; No need to save base pointer.
; NO_BASE_32-NOT: movl %ebx
; NO_BASE_32: mwaitx
; No need to restore base pointer.
; NO_BASE_32-NOT: movl {{.*}}, %ebx
; NO_BASE_32-NEXT: {{.+$}}
; Test of the case where an opaque sp adjustement is introduced by a separate
; basic block which, combined with stack realignment, requires a base pointer.
@g = global i32 0, align 8
define void @test_opaque_sp_adjustment(i32 %E, i32 %H, i32 %C, i64 %x) {
entry:
%ptr = alloca i8*, align 8
call void @llvm.x86.mwaitx(i32 %E, i32 %H, i32 %C)
%g = load i32, i32* @g, align 4
%tobool = icmp ne i32 %g, 0
br i1 %tobool, label %if.then, label %if.end
if.then:
call void asm sideeffect "", "~{rsp},~{esp},~{dirflag},~{fpsr},~{flags}"()
br label %if.end
if.end:
%ptr2 = load i8*, i8** %ptr, align 8
%arrayidx = getelementptr inbounds i8, i8* %ptr2, i64 %x
store volatile i8 42, i8* %arrayidx, align 1
ret void
}
; CHECK-LABEL: test_opaque_sp_adjustment:
; USE_BASE_64: movq %rsp, %rbx
; Pass mwaitx first 2 arguments in eax and ecx respectively.
; USE_BASE_64: movl %esi, %eax
; USE_BASE_64: movl %edi, %ecx
; Save base pointer.
; USE_BASE_64: movq %rbx, [[SAVE_rbx:%r([8-9]|1[0-5]|di|si)]]
; Set mwaitx ebx argument.
; USE_BASE_64: movl %edx, %ebx
; USE_BASE_64-NEXT: mwaitx
; Restore base pointer.
; USE_BASE_64-NEXT: movq [[SAVE_rbx]], %rbx
; USE_BASE_32: movl %esp, %ebx
; Pass mwaitx first 2 arguments in eax and ecx respectively.
; USE_BASE_32: movl %esi, %eax
; USE_BASE_32: movl %edi, %ecx
; Save base pointer.
; USE_BASE_32: movl %ebx, [[SAVE_ebx:%e(di|si)]]
; Set mwaitx ebx argument.
; USE_BASE_32: movl %edx, %ebx
; USE_BASE_32-NEXT: mwaitx
; Restore base pointer.
; USE_BASE_32-NEXT: movl [[SAVE_ebx]], %ebx
; Pass mwaitx 3 arguments in eax, ecx, ebx
; NO_BASE_64: movl %edx, %ebx
; NO_BASE_64: movl %esi, %eax
; NO_BASE_64: movl %edi, %ecx
; No need to save base pointer.
; NO_BASE_64-NOT: movq %rbx
; NO_BASE_64: mwaitx
; NO_BASE_64-NOT: movq {{.*}}, %rbx
; NO_BASE_64-NEXT: {{.+$}}
; Pass mwaitx 3 arguments in eax, ecx, ebx
; NO_BASE_32: movl %edx, %ebx
; NO_BASE_32: movl %esi, %eax
; NO_BASE_32: movl %edi, %ecx
; No need to save base pointer.
; NO_BASE_32-NOT: movl %ebx
; NO_BASE_32: mwaitx
; No need to restore base pointer.
; NO_BASE_32-NOT: movl {{.*}}, %ebx
; NO_BASE_32-NEXT: {{.+$}}
; Test of the case where a variable size object is introduced by a separate
; basic block which, combined with stack realignment, requires a base pointer.
define void @test_variable_size_object(i32 %E, i32 %H, i32 %C, i64 %x) {
entry:
%ptr = alloca i8*, align 8
call void @llvm.x86.mwaitx(i32 %E, i32 %H, i32 %C)
%g = load i32, i32* @g, align 4
%tobool = icmp ne i32 %g, 0
br i1 %tobool, label %if.then, label %if.end
if.then:
%i5 = alloca i8, i64 %x, align 16
store i8* %i5, i8** %ptr, align 8
br label %if.end
if.end:
%ptr2 = load i8*, i8** %ptr, align 8
%arrayidx = getelementptr inbounds i8, i8* %ptr2, i64 %x
store volatile i8 42, i8* %arrayidx, align 1
ret void
}
; CHECK-LABEL: test_variable_size_object:
; USE_BASE_64: movq %rsp, %rbx
; Pass mwaitx first 2 arguments in eax and ecx respectively.
; USE_BASE_64: movl %esi, %eax
; USE_BASE_64: movl %edi, %ecx
; Save base pointer.
; USE_BASE_64: movq %rbx, [[SAVE_rbx:%r([8-9]|1[0-5]|di|si)]]
; Set mwaitx ebx argument.
; USE_BASE_64: movl %edx, %ebx
; USE_BASE_64-NEXT: mwaitx
; Restore base pointer.
; USE_BASE_64-NEXT: movq [[SAVE_rbx]], %rbx
; USE_BASE_32: movl %esp, %ebx
; Pass mwaitx first 2 arguments in eax and ecx respectively.
; USE_BASE_32: movl %esi, %eax
; USE_BASE_32: movl %edi, %ecx
; Save base pointer.
; USE_BASE_32: movl %ebx, [[SAVE_ebx:%e(di|si)]]
; Set mwaitx ebx argument.
; USE_BASE_32: movl %edx, %ebx
; USE_BASE_32-NEXT: mwaitx
; Restore base pointer.
; USE_BASE_32-NEXT: movl [[SAVE_ebx]], %ebx
; Pass mwaitx 3 arguments in eax, ecx, ebx
; NO_BASE_64: movl %edx, %ebx
; NO_BASE_64: movl %esi, %eax
; NO_BASE_64: movl %edi, %ecx
; No need to save base pointer.
; NO_BASE_64-NOT: movq %rbx
; NO_BASE_64: mwaitx
; NO_BASE_64-NOT: movq {{.*}}, %rbx
; NO_BASE_64-NEXT: {{.+$}}
; Pass mwaitx 3 arguments in eax, ecx, ebx
; NO_BASE_32: movl %edx, %ebx
; NO_BASE_32: movl %esi, %eax
; NO_BASE_32: movl %edi, %ecx
; No need to save base pointer.
; NO_BASE_32-NOT: movl %ebx
; NO_BASE_32: mwaitx
; No need to restore base pointer.
; NO_BASE_32-NOT: movl {{.*}}, %ebx
; NO_BASE_32-NEXT: {{.+$}}
declare void @llvm.x86.mwaitx(i32, i32, i32) nounwind
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