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ec44dc9079
library call to __aeabi_uidivmod. This is an improved implementation of r280808, see also D24133, that got reverted because isel was stuck in a loop. That was caused by the optimisation incorrectly triggering on i64 ints, which shouldn't happen because there is no 64bit hwdiv support; that put isel's type legalization and this optimisation in a loop. A native ARM compiler and testing now shows that this is fixed. Patch mostly by Pablo Barrio. Differential Revision: https://reviews.llvm.org/D25077 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283098 91177308-0d34-0410-b5e6-96231b3b80d8
118 lines
4.0 KiB
LLVM
118 lines
4.0 KiB
LLVM
; When optimising for minimum size, we don't want to expand a div to a mul
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; and a shift sequence. As a result, the urem instruction e.g. will not be
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; expanded to a sequence of umull, lsrs, muls and sub instructions, but
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; just a call to __aeabi_uidivmod.
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;
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; When the processor features hardware division, UDIV + UREM can be turned
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; into UDIV + MLS. This prevents the library function __aeabi_uidivmod to be
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; pulled into the binary. The test uses ARMv7-M.
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;
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; RUN: llc -mtriple=armv7a-eabi -mattr=-neon -verify-machineinstrs %s -o - | FileCheck %s
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; RUN: llc -mtriple=thumbv7m-eabi -verify-machineinstrs %s -o - | FileCheck %s -check-prefix=V7M
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target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
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target triple = "thumbv7m-arm-none-eabi"
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define i32 @foo1() local_unnamed_addr #0 {
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entry:
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; CHECK-LABEL: foo1:
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; CHECK:__aeabi_idiv
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; CHECK-NOT: smmul
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%call = tail call i32 bitcast (i32 (...)* @GetValue to i32 ()*)()
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%div = sdiv i32 %call, 1000000
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ret i32 %div
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}
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define i32 @foo2() local_unnamed_addr #0 {
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entry:
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; CHECK-LABEL: foo2:
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; CHECK: __aeabi_uidiv
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; CHECK-NOT: umull
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%call = tail call i32 bitcast (i32 (...)* @GetValue to i32 ()*)()
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%div = udiv i32 %call, 1000000
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ret i32 %div
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}
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; Test for unsigned remainder
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define i32 @foo3() local_unnamed_addr #0 {
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entry:
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; CHECK-LABEL: foo3:
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; CHECK: __aeabi_uidivmod
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; CHECK-NOT: umull
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; V7M-LABEL: foo3:
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; V7M: udiv [[R2:r[0-9]+]], [[R0:r[0-9]+]], [[R1:r[0-9]+]]
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; V7M: mls {{r[0-9]+}}, [[R2]], [[R1]], [[R0]]
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; V7M-NOT: __aeabi_uidivmod
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%call = tail call i32 bitcast (i32 (...)* @GetValue to i32 ()*)()
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%rem = urem i32 %call, 1000000
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%cmp = icmp eq i32 %rem, 0
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%conv = zext i1 %cmp to i32
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ret i32 %conv
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}
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; Test for signed remainder
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define i32 @foo4() local_unnamed_addr #0 {
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entry:
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; CHECK-LABEL: foo4:
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; CHECK:__aeabi_idivmod
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; V7M-LABEL: foo4:
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; V7M: sdiv [[R2:r[0-9]+]], [[R0:r[0-9]+]], [[R1:r[0-9]+]]
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; V7M: mls {{r[0-9]+}}, [[R2]], [[R1]], [[R0]]
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; V7M-NOT: __aeabi_idivmod
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%call = tail call i32 bitcast (i32 (...)* @GetValue to i32 ()*)()
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%rem = srem i32 %call, 1000000
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ret i32 %rem
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}
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; Check that doing a sdiv+srem has the same effect as only the srem,
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; as the division needs to be computed anyway in order to calculate
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; the remainder (i.e. make sure we don't end up with two divisions).
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define i32 @foo5() local_unnamed_addr #0 {
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entry:
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; CHECK-LABEL: foo5:
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; CHECK:__aeabi_idivmod
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; V7M-LABEL: foo5:
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; V7M: sdiv [[R2:r[0-9]+]], [[R0:r[0-9]+]], [[R1:r[0-9]+]]
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; V7M-NOT: sdiv
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; V7M: mls {{r[0-9]+}}, [[R2]], [[R1]], [[R0]]
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; V7M-NOT: __aeabi_idivmod
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%call = tail call i32 bitcast (i32 (...)* @GetValue to i32 ()*)()
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%div = sdiv i32 %call, 1000000
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%rem = srem i32 %call, 1000000
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%add = add i32 %div, %rem
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ret i32 %add
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}
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; An early version of this patch caused isel to hang. The reason
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; was that it shouldn't do the rewrite for i64 because that's not
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; supported by hardware. Isel was stuck in a loop with type
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; legalization and this optimisation.
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; Function Attrs: norecurse nounwind
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define i64 @isel_dont_hang(i32 %bar) local_unnamed_addr #4 {
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entry:
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; CHECK-LABEL: isel_dont_hang:
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; CHECK: __aeabi_uldivmod
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%temp.0 = sext i32 %bar to i64
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%mul83 = shl i64 %temp.0, 1
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%add84 = add i64 %temp.0, 2
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%div85 = udiv i64 %mul83, %add84
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ret i64 %div85
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}
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; i16 types are promoted to i32, and we expect a normal udiv here:
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define i16 @isel_dont_hang_2(i16 %bar) local_unnamed_addr #4 {
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entry:
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; CHECK-LABEL: isel_dont_hang_2:
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; CHECK: udiv
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; CHECK-NOT: __aeabi_
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%mul83 = shl i16 %bar, 1
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%add84 = add i16 %bar, 2
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%div85 = udiv i16 %mul83, %add84
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ret i16 %div85
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}
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declare i32 @GetValue(...) local_unnamed_addr
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attributes #0 = { minsize nounwind optsize }
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attributes #4 = { norecurse nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-jump-tables"="false" "stack-protector-buffer-size"="8" "target-cpu"="cortex-a15" "target-features"="+dsp,+hwdiv,+hwdiv-arm,+neon,+vfp4" "use-soft-float"="false" }
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