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D33562.id.diff
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Fri, Jan 24, 4:28 PM

D33562.id.diff

Index: llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
===================================================================
--- llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
+++ llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
@@ -497,6 +497,16 @@
/// function. Used by MachineRegisterInfo::isConstantPhysReg().
virtual bool isConstantPhysReg(unsigned PhysReg) const { return false; }
+ /// Physical registers that may be modified within a function but are
+ /// guaranteed to be restored before any uses. This is useful for targets that
+ /// have call sequences where a GOT register may be updated by the caller
+ /// prior to a call and is guaranteed to be restored (also by the caller)
+ /// after the call.
+ virtual bool isCallerPreservedPhysReg(unsigned PhysReg,
+ const MachineFunction &MF) const {
+ return false;
+ }
+
/// Prior to adding the live-out mask to a stackmap or patchpoint
/// instruction, provide the target the opportunity to adjust it (mainly to
/// remove pseudo-registers that should be ignored).
Index: llvm/trunk/lib/CodeGen/MachineLICM.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MachineLICM.cpp
+++ llvm/trunk/lib/CodeGen/MachineLICM.cpp
@@ -895,8 +895,11 @@
// If the physreg has no defs anywhere, it's just an ambient register
// and we can freely move its uses. Alternatively, if it's allocatable,
// it could get allocated to something with a def during allocation.
- if (!MRI->isConstantPhysReg(Reg))
- return false;
+ // However, if the physreg is known to always be caller saved/restored
+ // then this use is safe to hoist.
+ if (!MRI->isConstantPhysReg(Reg) &&
+ !(TRI->isCallerPreservedPhysReg(Reg, *I.getParent()->getParent())))
+ return false;
// Otherwise it's safe to move.
continue;
} else if (!MO.isDead()) {
Index: llvm/trunk/lib/Target/PowerPC/PPCRegisterInfo.h
===================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCRegisterInfo.h
+++ llvm/trunk/lib/Target/PowerPC/PPCRegisterInfo.h
@@ -83,6 +83,7 @@
void adjustStackMapLiveOutMask(uint32_t *Mask) const override;
BitVector getReservedRegs(const MachineFunction &MF) const override;
+ bool isCallerPreservedPhysReg(unsigned PhysReg, const MachineFunction &MF) const override;
/// We require the register scavenger.
bool requiresRegisterScavenging(const MachineFunction &MF) const override {
Index: llvm/trunk/lib/Target/PowerPC/PPCRegisterInfo.cpp
===================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ llvm/trunk/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -273,6 +273,20 @@
return Reserved;
}
+bool PPCRegisterInfo::isCallerPreservedPhysReg(unsigned PhysReg,
+ const MachineFunction &MF) const {
+ assert(TargetRegisterInfo::isPhysicalRegister(PhysReg));
+ if (TM.isELFv2ABI() && PhysReg == PPC::X2) {
+ // X2 is guaranteed to be preserved within a function if it is reserved.
+ // The reason it's reserved is that it's the TOC pointer (and the function
+ // uses the TOC). In functions where it isn't reserved (i.e. leaf functions
+ // with no TOC access), we can't claim that it is preserved.
+ return (getReservedRegs(MF).test(PPC::X2));
+ } else {
+ return false;
+ }
+}
+
unsigned PPCRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
MachineFunction &MF) const {
const PPCFrameLowering *TFI = getFrameLowering(MF);
Index: llvm/trunk/test/CodeGen/PowerPC/licm-tocReg.ll
===================================================================
--- llvm/trunk/test/CodeGen/PowerPC/licm-tocReg.ll
+++ llvm/trunk/test/CodeGen/PowerPC/licm-tocReg.ll
@@ -0,0 +1,110 @@
+; RUN: llc -verify-machineinstrs -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
+
+; The instructions ADDIStocHA/LDtocL are used to calculate the address of
+; globals. The ones that are in bb.3.if.end could not be hoisted by Machine
+; LICM due to BCTRL_LDinto_toc in bb2.if.then. This call causes the compiler
+; to insert a save TOC to stack before the call and load into X2 to restore TOC
+; after. By communicating to Machine LICM that X2 is guaranteed to have the
+; same value before and after BCTRL_LDinto_toc, these instructions can be
+; hoisted out of bb.3.if.end to outside of the loop.
+
+; Pre Machine LICM MIR
+;
+;body:
+; bb.0.entry:
+; successors: %bb.2.if.then(0x40000000), %bb.3.if.end(0x40000000)
+; liveins: %x3
+;
+; %4 = COPY %x3
+; %5 = ADDIStocHA %x2, @ga
+; %6 = LDtocL @ga, killed %5 :: (load 8 from got)
+; %7 = LWZ 0, %6 :: (volatile dereferenceable load 4 from @ga)
+; %8 = ADDIStocHA %x2, @gb
+; %9 = LDtocL @gb, killed %8 :: (load 8 from got)
+; %10 = LWZ 0, killed %9 :: (volatile dereferenceable load 4 from @gb)
+; %0 = LWZ 0, %6 :: (volatile dereferenceable load 4 from @ga)
+; %11 = CMPW killed %7, killed %10
+; BCC 44, killed %11, %bb.2.if.then
+; B %bb.3.if.end
+;
+; bb.2.if.then:
+; %1 = PHI %0, %bb.0.entry, %3, %bb.3.if.end
+; ADJCALLSTACKDOWN 32, 0, implicit-def dead %r1, implicit %r1
+; %20 = COPY %x2
+; STD %20, 24, %x1 :: (store 8 into stack + 24)
+; %21 = EXTSW_32_64 %1
+; %x3 = COPY %21
+; %x12 = COPY %4
+; MTCTR8 %4, implicit-def %ctr8
+; BCTRL8_LDinto_toc 24, %x1, csr_svr464_altivec, implicit-def dead %lr8, implicit-def dead %x2, implicit %ctr8, implicit %rm, implicit %x3, implicit %x12, implicit %x2, implicit-def %r1, implicit-def %x3
+; ADJCALLSTACKUP 32, 0, implicit-def dead %r1, implicit %r1
+; %22 = COPY %x3
+; %x3 = COPY %22
+; BLR8 implicit %lr8, implicit %rm, implicit %x3
+;
+; bb.3.if.end:
+; successors: %bb.2.if.then(0x04000000), %bb.3.if.end(0x7c000000)
+;
+; %2 = PHI %0, %bb.0.entry, %3, %bb.3.if.end
+; %12 = ADDI %2, 1
+; %13 = ADDIStocHA %x2, @ga
+; %14 = LDtocL @ga, killed %13 :: (load 8 from got)
+; STW killed %12, 0, %14 :: (volatile store 4 into @ga)
+; %15 = LWZ 0, %14 :: (volatile dereferenceable load 4 from @ga)
+; %16 = ADDIStocHA %x2, @gb
+; %17 = LDtocL @gb, killed %16 :: (load 8 from got)
+; %18 = LWZ 0, killed %17 :: (volatile dereferenceable load 4 from @gb)
+; %3 = LWZ 0, %14 :: (volatile dereferenceable load 4 from @ga)
+; %19 = CMPW killed %15, killed %18
+; BCC 44, killed %19, %bb.2.if.then
+; B %bb.3.if.end
+
+@ga = external global i32, align 4
+@gb = external global i32, align 4
+
+; Function Attrs: nounwind
+define signext i32 @test(i32 (i32)* nocapture %FP) local_unnamed_addr #0 {
+; CHECK-LABEL: test:
+; CHECK: # BB#0: # %entry
+; CHECK-NEXT: addis 4, 2, .LC0@toc@ha
+; CHECK-NEXT: addis 5, 2, .LC1@toc@ha
+; CHECK-NEXT: ld 4, .LC0@toc@l(4)
+; CHECK-NEXT: ld 5, .LC1@toc@l(5)
+; CHECK-NEXT: lwz 6, 0(4)
+; CHECK-NEXT: lwz 5, 0(5)
+; CHECK-NEXT: cmpw 6, 5
+; CHECK-NEXT: lwz 5, 0(4)
+; CHECK-NEXT: mr 4, 3
+; CHECK-NEXT: bgt 0, .LBB0_3
+; CHECK-NEXT: # BB#1:
+; CHECK-NEXT: addis 3, 2, .LC0@toc@ha
+; CHECK-NEXT: addis 6, 2, .LC1@toc@ha
+; CHECK-NEXT: ld 3, .LC0@toc@l(3)
+; CHECK-NEXT: ld 6, .LC1@toc@l(6)
+; CHECK-NEXT: .p2align 5
+; CHECK-NEXT: .LBB0_2: # %if.end
+; CHECK-NOT: addis {{[0-9]+}}, 2, .LC0@toc@ha
+; CHECK-NOT: addis {{[0-9]+}}, 2, .LC1@toc@ha
+; CHECK: blr
+entry:
+ %0 = load volatile i32, i32* @ga, align 4
+ %1 = load volatile i32, i32* @gb, align 4
+ %cmp1 = icmp sgt i32 %0, %1
+ %2 = load volatile i32, i32* @ga, align 4
+ br i1 %cmp1, label %if.then, label %if.end
+
+if.then: ; preds = %if.end, %entry
+ %.lcssa = phi i32 [ %2, %entry ], [ %6, %if.end ]
+ %call = tail call signext i32 %FP(i32 signext %.lcssa) #1
+ ret i32 %call
+
+if.end: ; preds = %entry, %if.end
+ %3 = phi i32 [ %6, %if.end ], [ %2, %entry ]
+ %inc = add nsw i32 %3, 1
+ store volatile i32 %inc, i32* @ga, align 4
+ %4 = load volatile i32, i32* @ga, align 4
+ %5 = load volatile i32, i32* @gb, align 4
+ %cmp = icmp sgt i32 %4, %5
+ %6 = load volatile i32, i32* @ga, align 4
+ br i1 %cmp, label %if.then, label %if.end
+}

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