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llvm-mirror/test/CodeGen/ARM/sdiv-pow2-thumb-size.ll
Sjoerd Meijer 532a78148a [ARM] Don't expand sdiv when optimising for minsize
Don't expand SDIV with an immediate that is a power of 2 if we optimise for
minimum code size. For example:

sdiv %1, i32 4

gets expanded to a sequence of 3 instructions, but this is suboptimal for
minimum code size so instead we just generate a MOV and a SDIV if integer
division is supported.

Differential Revision: https://reviews.llvm.org/D54546

llvm-svn: 347965
2018-11-30 08:14:28 +00:00

106 lines
2.6 KiB
LLVM

; RUN: llc -mtriple=thumbv8 %s -o - | FileCheck %s --check-prefixes=CHECK,T2
; RUN: llc -mtriple=thumbv8m.main %s -o - | FileCheck %s --check-prefixes=CHECK,T2
; RUN: llc -mtriple=thumbv8m.base %s -o - | FileCheck %s --check-prefixes=CHECK,T1
; RUN: llc -mtriple=thumbv7em %s -o - | FileCheck %s --check-prefixes=CHECK,T2
; RUN: llc -mtriple=thumbv6m %s -o - | FileCheck %s --check-prefixes=V6M
; Armv6m targets don't have a sdiv instruction, so sdiv should not appear at
; all in the output:
; V6M: .file {{.*}}
; V6M-NOT: sdiv
; V6M-NOT: idiv
; Test sdiv i16
define dso_local signext i16 @f0(i16 signext %F) local_unnamed_addr #0 {
; CHECK-LABEL: f0
; CHECK: movs r1, #2
; CHECK-NEXT: sdiv r0, r0, r1
; CHECK-NEXT: sxth r0, r0
; CHECK-NEXT: bx lr
entry:
%0 = sdiv i16 %F, 2
ret i16 %0
}
; Same as above, but now with i32
define dso_local i32 @f1(i32 %F) local_unnamed_addr #0 {
; CHECK-LABEL: f1
; CHECK: movs r1, #4
; CHECK-NEXT: sdiv r0, r0, r1
; CHECK-NEXT: bx lr
entry:
%div = sdiv i32 %F, 4
ret i32 %div
}
; The immediate is not a power of 2, so we expect a sdiv.
define dso_local i32 @f2(i32 %F) local_unnamed_addr #0 {
; CHECK-LABEL: f2
; CHECK: movs r1, #5
; CHECK-NEXT: sdiv r0, r0, r1
; CHECK-NEXT: bx lr
entry:
%div = sdiv i32 %F, 5
ret i32 %div
}
; Try a larger power of 2 immediate: immediates larger than
; 128 don't give any code size savings.
define dso_local i32 @f3(i32 %F) local_unnamed_addr #0 {
; CHECK-LABEL: f3
; CHECK-NOT: sdiv
entry:
%div = sdiv i32 %F, 256
ret i32 %div
}
attributes #0 = { minsize norecurse nounwind optsize readnone }
; These functions don't have the minsize attribute set, so should not lower
; the sdiv to sdiv, but to the faster instruction sequence.
define dso_local signext i16 @f4(i16 signext %F) {
; T2-LABEL: f4
; T2: uxth r1, r0
; T2-NEXT: add.w r0, r0, r1, lsr #15
; T2-NEXT: sxth r0, r0
; T2-NEXT: asrs r0, r0, #1
; T2-NEXT: bx lr
; T1-LABEL: f4
; T1: uxth r1, r0
; T1-NEXT: lsrs r1, r1, #15
; T1-NEXT: adds r0, r0, r1
; T1-NEXT: sxth r0, r0
; T1-NEXT: asrs r0, r0, #1
; T1-NEXT: bx lr
entry:
%0 = sdiv i16 %F, 2
ret i16 %0
}
define dso_local i32 @f5(i32 %F) {
; T2-LABEL: f5
; T2: asrs r1, r0, #31
; T2-NEXT: add.w r0, r0, r1, lsr #30
; T2-NEXT: asrs r0, r0, #2
; T2-NEXT: bx lr
; T1-LABEL: f5
; T1: asrs r1, r0, #31
; T1-NEXT: lsrs r1, r1, #30
; T1-NEXT: adds r0, r0, r1
; T1-NEXT: asrs r0, r0, #2
; T1-NEXT: bx lr
entry:
%div = sdiv i32 %F, 4
ret i32 %div
}