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[ARM] Fix inline memcpy trip count sequence

The trip count for a memcpy/memset will be n/16 rounded up to the
nearest integer. So (n+15)>>4. The old code was including a BIC too, to
clear one of the bits, which does not seem correct. This remove the
extra BIC.

Note that ideally this would never actually be generated, as in the
creation of a tail predicated loop we will DCE that setup code, letting
the WLSTP perform the trip count calculation. So this doesn't usually
come up in testing (and apparently the ARMLowOverheadLoops pass does not
do any sort of validation on the tripcount). Only if the generation of
the WLTP fails will it use the incorrect BIC instructions.

Differential Revision: https://reviews.llvm.org/D102629
This commit is contained in:
David Green 2021-05-24 11:01:58 +01:00
parent f5b495a5df
commit 5c433e70b6
4 changed files with 26 additions and 38 deletions

View File

@ -11110,7 +11110,7 @@ static Register genTPEntry(MachineBasicBlock *TpEntry,
MachineBasicBlock *TpExit, Register OpSizeReg,
const TargetInstrInfo *TII, DebugLoc Dl,
MachineRegisterInfo &MRI) {
// Calculates loop iteration count = ceil(n/16)/16 = ((n + 15)&(-16)) / 16.
// Calculates loop iteration count = ceil(n/16) = (n + 15) >> 4.
Register AddDestReg = MRI.createVirtualRegister(&ARM::rGPRRegClass);
BuildMI(TpEntry, Dl, TII->get(ARM::t2ADDri), AddDestReg)
.addUse(OpSizeReg)
@ -11118,16 +11118,9 @@ static Register genTPEntry(MachineBasicBlock *TpEntry,
.add(predOps(ARMCC::AL))
.addReg(0);
Register BicDestReg = MRI.createVirtualRegister(&ARM::rGPRRegClass);
BuildMI(TpEntry, Dl, TII->get(ARM::t2BICri), BicDestReg)
.addUse(AddDestReg, RegState::Kill)
.addImm(16)
.add(predOps(ARMCC::AL))
.addReg(0);
Register LsrDestReg = MRI.createVirtualRegister(&ARM::GPRlrRegClass);
Register LsrDestReg = MRI.createVirtualRegister(&ARM::rGPRRegClass);
BuildMI(TpEntry, Dl, TII->get(ARM::t2LSRri), LsrDestReg)
.addUse(BicDestReg, RegState::Kill)
.addUse(AddDestReg, RegState::Kill)
.addImm(4)
.add(predOps(ARMCC::AL))
.addReg(0);

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@ -235,7 +235,6 @@ define void @test11(i8* nocapture %x, i8* nocapture %y, i32 %n) {
; CHECK-NEXT: .LBB10_1: @ %prehead
; CHECK-NEXT: add.w r3, r2, #15
; CHECK-NEXT: mov r12, r1
; CHECK-NEXT: bic r3, r3, #16
; CHECK-NEXT: mov r4, r0
; CHECK-NEXT: lsr.w lr, r3, #4
; CHECK-NEXT: mov r3, r2
@ -326,11 +325,11 @@ define void @twoloops(i32* %X, i32 %n, i32 %m) {
; CHECK-NEXT: .save {r7, lr}
; CHECK-NEXT: push {r7, lr}
; CHECK-NEXT: vmov.i32 q0, #0x0
; CHECK-NEXT: mov r3, r2
; CHECK-NEXT: mov r1, r0
; CHECK-NEXT: wlstp.8 lr, r3, .LBB13_2
; CHECK-NEXT: mov r3, r0
; CHECK-NEXT: mov r1, r2
; CHECK-NEXT: wlstp.8 lr, r1, .LBB13_2
; CHECK-NEXT: .LBB13_1: @ =>This Inner Loop Header: Depth=1
; CHECK-NEXT: vstrb.8 q0, [r1], #16
; CHECK-NEXT: vstrb.8 q0, [r3], #16
; CHECK-NEXT: letp lr, .LBB13_1
; CHECK-NEXT: .LBB13_2: @ %entry
; CHECK-NEXT: wlstp.8 lr, r2, .LBB13_4

View File

@ -197,8 +197,8 @@ define dso_local i32 @e() #0 {
; CHECK-NEXT: vmov.32 q4[0], r8
; CHECK-NEXT: @ implicit-def: $r2
; CHECK-NEXT: str.w r8, [sp, #52]
; CHECK-NEXT: strh.w r12, [sp, #414]
; CHECK-NEXT: vstrw.32 q3, [sp, #68]
; CHECK-NEXT: strh.w r12, [sp, #414]
; CHECK-NEXT: wlstp.8 lr, r1, .LBB1_2
; CHECK-NEXT: .LBB1_1: @ =>This Inner Loop Header: Depth=1
; CHECK-NEXT: vldrw.u32 q0, [sp] @ 16-byte Reload

View File

@ -67,15 +67,14 @@ body: |
; CHECK: [[COPY1:%[0-9]+]]:rgpr = COPY $r1
; CHECK: [[COPY2:%[0-9]+]]:rgpr = COPY $r0
; CHECK: [[t2ADDri:%[0-9]+]]:rgpr = t2ADDri [[COPY]], 15, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2BICri:%[0-9]+]]:rgpr = t2BICri killed [[t2ADDri]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:gprlr = t2LSRri killed [[t2BICri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:rgpr = t2LSRri killed [[t2ADDri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2WhileLoopSetup:%[0-9]+]]:gprlr = t2WhileLoopSetup killed [[t2LSRri]]
; CHECK: t2WhileLoopStart [[t2WhileLoopSetup]], %bb.2, implicit-def $cpsr
; CHECK: .1:
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY1]], %bb.0, %8, %bb.1
; CHECK: [[PHI1:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.0, %10, %bb.1
; CHECK: [[PHI2:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.0, %12, %bb.1
; CHECK: [[PHI3:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.0, %14, %bb.1
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY1]], %bb.0, %7, %bb.1
; CHECK: [[PHI1:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.0, %9, %bb.1
; CHECK: [[PHI2:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.0, %11, %bb.1
; CHECK: [[PHI3:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.0, %13, %bb.1
; CHECK: [[MVE_VCTP8_:%[0-9]+]]:vccr = MVE_VCTP8 [[PHI3]], 0, $noreg
; CHECK: [[t2SUBri:%[0-9]+]]:rgpr = t2SUBri [[PHI3]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[MVE_VLDRBU8_post:%[0-9]+]]:rgpr, [[MVE_VLDRBU8_post1:%[0-9]+]]:mqpr = MVE_VLDRBU8_post [[PHI]], 16, 1, [[MVE_VCTP8_]]
@ -108,15 +107,14 @@ body: |
; CHECK: t2B %bb.1, 14 /* CC::al */, $noreg
; CHECK: bb.1.for.body.preheader:
; CHECK: [[t2ADDri:%[0-9]+]]:rgpr = t2ADDri [[COPY]], 15, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2BICri:%[0-9]+]]:rgpr = t2BICri killed [[t2ADDri]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:gprlr = t2LSRri killed [[t2BICri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:rgpr = t2LSRri killed [[t2ADDri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2WhileLoopSetup:%[0-9]+]]:gprlr = t2WhileLoopSetup killed [[t2LSRri]]
; CHECK: t2WhileLoopStart [[t2WhileLoopSetup]], %bb.4, implicit-def $cpsr
; CHECK: bb.3:
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY1]], %bb.1, %8, %bb.3
; CHECK: [[PHI1:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.1, %10, %bb.3
; CHECK: [[PHI2:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.1, %12, %bb.3
; CHECK: [[PHI3:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.1, %14, %bb.3
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY1]], %bb.1, %7, %bb.3
; CHECK: [[PHI1:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.1, %9, %bb.3
; CHECK: [[PHI2:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.1, %11, %bb.3
; CHECK: [[PHI3:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.1, %13, %bb.3
; CHECK: [[MVE_VCTP8_:%[0-9]+]]:vccr = MVE_VCTP8 [[PHI3]], 0, $noreg
; CHECK: [[t2SUBri:%[0-9]+]]:rgpr = t2SUBri [[PHI3]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[MVE_VLDRBU8_post:%[0-9]+]]:rgpr, [[MVE_VLDRBU8_post1:%[0-9]+]]:mqpr = MVE_VLDRBU8_post [[PHI]], 16, 1, [[MVE_VCTP8_]]
@ -161,14 +159,13 @@ body: |
; CHECK: [[COPY1:%[0-9]+]]:mqpr = COPY $r1
; CHECK: [[COPY2:%[0-9]+]]:rgpr = COPY $r0
; CHECK: [[t2ADDri:%[0-9]+]]:rgpr = t2ADDri [[COPY]], 15, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2BICri:%[0-9]+]]:rgpr = t2BICri killed [[t2ADDri]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:gprlr = t2LSRri killed [[t2BICri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:rgpr = t2LSRri killed [[t2ADDri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2WhileLoopSetup:%[0-9]+]]:gprlr = t2WhileLoopSetup killed [[t2LSRri]]
; CHECK: t2WhileLoopStart [[t2WhileLoopSetup]], %bb.2, implicit-def $cpsr
; CHECK: .1:
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.0, %8, %bb.1
; CHECK: [[PHI1:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.0, %10, %bb.1
; CHECK: [[PHI2:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.0, %12, %bb.1
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.0, %7, %bb.1
; CHECK: [[PHI1:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.0, %9, %bb.1
; CHECK: [[PHI2:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.0, %11, %bb.1
; CHECK: [[MVE_VCTP8_:%[0-9]+]]:vccr = MVE_VCTP8 [[PHI2]], 0, $noreg
; CHECK: [[t2SUBri:%[0-9]+]]:rgpr = t2SUBri [[PHI2]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[MVE_VSTRBU8_post:%[0-9]+]]:rgpr = MVE_VSTRBU8_post [[COPY1]], [[PHI]], 16, 1, [[MVE_VCTP8_]]
@ -201,14 +198,13 @@ body: |
; CHECK: t2B %bb.1, 14 /* CC::al */, $noreg
; CHECK: bb.1.for.body.preheader:
; CHECK: [[t2ADDri:%[0-9]+]]:rgpr = t2ADDri [[COPY]], 15, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2BICri:%[0-9]+]]:rgpr = t2BICri killed [[t2ADDri]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:gprlr = t2LSRri killed [[t2BICri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2LSRri:%[0-9]+]]:rgpr = t2LSRri killed [[t2ADDri]], 4, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[t2WhileLoopSetup:%[0-9]+]]:gprlr = t2WhileLoopSetup killed [[t2LSRri]]
; CHECK: t2WhileLoopStart [[t2WhileLoopSetup]], %bb.4, implicit-def $cpsr
; CHECK: bb.3:
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.1, %8, %bb.3
; CHECK: [[PHI1:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.1, %10, %bb.3
; CHECK: [[PHI2:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.1, %12, %bb.3
; CHECK: [[PHI:%[0-9]+]]:rgpr = PHI [[COPY2]], %bb.1, %7, %bb.3
; CHECK: [[PHI1:%[0-9]+]]:gprlr = PHI [[t2WhileLoopSetup]], %bb.1, %9, %bb.3
; CHECK: [[PHI2:%[0-9]+]]:rgpr = PHI [[COPY]], %bb.1, %11, %bb.3
; CHECK: [[MVE_VCTP8_:%[0-9]+]]:vccr = MVE_VCTP8 [[PHI2]], 0, $noreg
; CHECK: [[t2SUBri:%[0-9]+]]:rgpr = t2SUBri [[PHI2]], 16, 14 /* CC::al */, $noreg, $noreg
; CHECK: [[MVE_VSTRBU8_post:%[0-9]+]]:rgpr = MVE_VSTRBU8_post [[COPY1]], [[PHI]], 16, 1, [[MVE_VCTP8_]]