diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.h b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
@@ -336,6 +336,9 @@
bool FoldImmediate(MachineInstr &UseMI, MachineInstr &DefMI, Register Reg,
MachineRegisterInfo *MRI) const override;
+ bool onlyFoldImmediate(MachineInstr &UseMI, MachineInstr &DefMI,
+ Register Reg) const;
+
// If conversion by predication (only supported by some branch instructions).
// All of the profitability checks always return true; it is always
// profitable to use the predicated branches.
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -1350,9 +1350,11 @@
return false;
}
-bool PPCInstrInfo::FoldImmediate(MachineInstr &UseMI, MachineInstr &DefMI,
- Register Reg, MachineRegisterInfo *MRI) const {
- // For some instructions, it is legal to fold ZERO into the RA register field.
+// For some instructions, it is legal to fold ZERO into the RA register field.
+// This function performs that fold by replacing the operand with PPC::ZERO,
+// it does not consider whether the load immediate zero is no longer in use.
+bool PPCInstrInfo::onlyFoldImmediate(MachineInstr &UseMI, MachineInstr &DefMI,
+ Register Reg) const {
// A zero immediate should always be loaded with a single li.
unsigned DefOpc = DefMI.getOpcode();
if (DefOpc != PPC::LI && DefOpc != PPC::LI8)
@@ -1372,6 +1374,8 @@
if (UseMCID.isPseudo())
return false;
+ // We need to find which of the User's operands is to be folded, that will be
+ // the operand that matches the given register ID.
unsigned UseIdx;
for (UseIdx = 0; UseIdx < UseMI.getNumOperands(); ++UseIdx)
if (UseMI.getOperand(UseIdx).isReg() &&
@@ -1409,13 +1413,19 @@
PPC::ZERO8 : PPC::ZERO;
}
- bool DeleteDef = MRI->hasOneNonDBGUse(Reg);
UseMI.getOperand(UseIdx).setReg(ZeroReg);
+ return true;
+}
- if (DeleteDef)
+// Folds zero into instructions which have a load immediate zero as an operand
+// but also recognize zero as immediate zero. If the definition of the load
+// has no more users it is deleted.
+bool PPCInstrInfo::FoldImmediate(MachineInstr &UseMI, MachineInstr &DefMI,
+ Register Reg, MachineRegisterInfo *MRI) const {
+ bool Changed = onlyFoldImmediate(UseMI, DefMI, Reg);
+ if (MRI->use_nodbg_empty(Reg))
DefMI.eraseFromParent();
-
- return true;
+ return Changed;
}
static bool MBBDefinesCTR(MachineBasicBlock &MBB) {
diff --git a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
--- a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
+++ b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
@@ -57,6 +57,8 @@
"Number of pairs of rotate left, clear left/right collapsed");
STATISTIC(NumEXTSWAndSLDICombined,
"Number of pairs of EXTSW and SLDI combined as EXTSWSLI");
+STATISTIC(NumLoadImmZeroFoldedAndRemoved,
+ "Number of LI(8) reg, 0 that are folded to r0 and removed");
static cl::opt<bool>
FixedPointRegToImm("ppc-reg-to-imm-fixed-point", cl::Hidden, cl::init(true),
@@ -319,7 +321,22 @@
default:
break;
-
+ case PPC::LI:
+ case PPC::LI8: {
+ // If we are materializing a zero, look for any use operands for which
+ // zero means immediate zero. All such operands can be replaced with
+ // PPC::ZERO.
+ if (!MI.getOperand(1).isImm() || MI.getOperand(1).getImm() != 0)
+ break;
+ unsigned MIDestReg = MI.getOperand(0).getReg();
+ for (MachineInstr& UseMI : MRI->use_instructions(MIDestReg))
+ Simplified |= TII->onlyFoldImmediate(UseMI, MI, MIDestReg);
+ if (MRI->use_nodbg_empty(MIDestReg)) {
+ ++NumLoadImmZeroFoldedAndRemoved;
+ ToErase = &MI;
+ }
+ break;
+ }
case PPC::STD: {
MachineFrameInfo &MFI = MF->getFrameInfo();
if (MFI.hasVarSizedObjects() ||
diff --git a/llvm/test/CodeGen/PowerPC/convert-rr-to-ri-instrs.mir b/llvm/test/CodeGen/PowerPC/convert-rr-to-ri-instrs.mir
--- a/llvm/test/CodeGen/PowerPC/convert-rr-to-ri-instrs.mir
+++ b/llvm/test/CodeGen/PowerPC/convert-rr-to-ri-instrs.mir
@@ -1615,7 +1615,7 @@
%0 = LI8 89
%2 = CMPDI %0, 87
%4 = ISEL8 $zero8, %0, %2.sub_gt
- ; CHECK: LI8 0
+ ; CHECK: ADDI8 %1, 0
%5 = ADD8 killed %4, %1
$x3 = COPY %5
BLR8 implicit $lr8, implicit $rm, implicit $x3
@@ -2017,7 +2017,7 @@
%3 = LI -3
%4 = CMPLWI %3, 87
%6 = ISEL $zero, %3, %4.sub_gt
- ; CHECK: LI 0
+ ; CHECK: ADDI killed %2, 0
%7 = ADD4 killed %6, killed %2
%9 = IMPLICIT_DEF
%8 = INSERT_SUBREG %9, killed %7, 1
diff --git a/llvm/test/CodeGen/PowerPC/fold-remove-li.ll b/llvm/test/CodeGen/PowerPC/fold-remove-li.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/fold-remove-li.ll
@@ -0,0 +1,40 @@
+; NOTE: This test verifies that a redundant load immediate of zero is folded
+; NOTE: from its use in an isel and deleted as it is no longer in use.
+; RUN: llc -mcpu=pwr9 -mtriple=powerpc64le-unknown-linux-gnu \
+; RUN: -ppc-asm-full-reg-names -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mcpu=pwr9 -mtriple=powerpc64-unknown-linux-gnu \
+; RUN: -ppc-asm-full-reg-names -verify-machineinstrs < %s | FileCheck %s
+
+%0 = type { i32, i16 }
+
+@val = common dso_local local_unnamed_addr global %0* null, align 8
+
+define dso_local signext i32 @redunLoadImm(%0* %arg) {
+; CHECK-LABEL: redunLoadImm:
+; verify that the load immediate has been folded into the isel and deleted
+; CHECK-NOT: li r[[REG1:[0-9]+]], 0
+; CHECK: isel r[[REG2:[0-9]+]], 0, r[[REG3:[0-9]+]], eq
+
+bb:
+ %tmp = icmp eq %0* %arg, null
+ br i1 %tmp, label %bb9, label %bb1
+
+bb1: ; preds = %bb
+ %tmp2 = getelementptr inbounds %0, %0* %arg, i64 0, i32 1
+ br label %bb3
+
+bb3: ; preds = %bb3, %bb1
+ %tmp4 = load i16, i16* %tmp2, align 4
+ %tmp5 = sext i16 %tmp4 to i64
+ %tmp6 = getelementptr inbounds %0, %0* %arg, i64 %tmp5
+ %tmp7 = icmp eq i16 %tmp4, 0
+ %tmp8 = select i1 %tmp7, %0* null, %0* %tmp6
+ store %0* %tmp8, %0** @val, align 8
+ br label %bb3
+
+bb9: ; preds = %bb
+ %tmp10 = load %0*, %0** @val, align 8
+ %tmp11 = getelementptr inbounds %0, %0* %tmp10, i64 0, i32 0
+ %tmp12 = load i32, i32* %tmp11, align 4
+ ret i32 %tmp12
+}
diff --git a/llvm/test/CodeGen/PowerPC/save-crbp-ppc32svr4.ll b/llvm/test/CodeGen/PowerPC/save-crbp-ppc32svr4.ll
--- a/llvm/test/CodeGen/PowerPC/save-crbp-ppc32svr4.ll
+++ b/llvm/test/CodeGen/PowerPC/save-crbp-ppc32svr4.ll
@@ -13,8 +13,7 @@
; CHECK: addic 29, 0, 20
; Save CR through R12 using R29 as the stack pointer (aligned base pointer).
; CHECK: mfcr 12
-; CHECK: stw 28, -24(29)
-; CHECK: stw 12, -28(29)
+; CHECK: stw 12, -24(29)
target datalayout = "E-m:e-p:32:32-i64:64-n32"
target triple = "powerpc-unknown-freebsd"