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llvm-mirror/test/CodeGen/SystemZ/stack-guard.ll
James Clarke 38b58c28d1 Use SETNE directly rather than SUB/SETNE 0 for stack guard check
Summary:
Backends should fold the subtraction into the comparison, but not all
seem to. Moreover, on targets where pointers are not integers, such as
CHERI, an integer subtraction is not appropriate. Instead we should just
compare the two pointers directly, as this should work everywhere and
potentially generate more efficient code.

Reviewers: bogner, lebedev.ri, efriedma, t.p.northover, uweigand, sunfish

Reviewed By: lebedev.ri

Subscribers: dschuff, sbc100, arichardson, jgravelle-google, hiraditya, aheejin, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74454
2020-02-18 13:21:26 +00:00

36 lines
1.0 KiB
LLVM

; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
; CHECK-LABEL: @test_stack_guard
; CHECK: ear [[REG1:%r[1-9][0-9]?]], %a0
; CHECK: sllg [[REG1]], [[REG1]], 32
; CHECK: ear [[REG1]], %a1
; CHECK: lg [[REG1]], 40([[REG1]])
; CHECK: stg [[REG1]], {{[0-9]*}}(%r15)
; CHECK: brasl %r14, foo3@PLT
; CHECK: ear [[REG2:%r[1-9][0-9]?]], %a0
; CHECK: sllg [[REG2]], [[REG2]], 32
; CHECK: ear [[REG2]], %a1
; CHECK: lg [[REG2]], 40([[REG2]])
; CHECK: cg [[REG2]], {{[0-9]*}}(%r15)
define i32 @test_stack_guard() #0 {
entry:
%a1 = alloca [256 x i32], align 4
%0 = bitcast [256 x i32]* %a1 to i8*
call void @llvm.lifetime.start.p0i8(i64 1024, i8* %0)
%arraydecay = getelementptr inbounds [256 x i32], [256 x i32]* %a1, i64 0, i64 0
call void @foo3(i32* %arraydecay)
call void @llvm.lifetime.end.p0i8(i64 1024, i8* %0)
ret i32 0
}
; Function Attrs: nounwind
declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
declare void @foo3(i32*)
; Function Attrs: nounwind
declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
attributes #0 = { sspstrong }