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From 5423496713e84dea2650e1703821de620f934573 Mon Sep 17 00:00:00 2001
From: Nemanja Ivanovic <nemanja.i.ibm@gmail.com>
Date: Thu, 9 Apr 2020 21:34:30 -0500
Subject: [PATCH] [PowerPC] Bail out of redundant LI elimination on an implicit
kill
The transformation currently does not differentiate between explicit
and implicit kills. However, it is not valid to later simply clear
an implicit kill flag since the kill could be due to a call or return.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=45374
---
.../lib/Target/PowerPC/PPCPreEmitPeephole.cpp | 10 ++
.../remove-redundant-li-skip-imp-kill.mir | 114 ++++++++++++++++++
2 files changed, 124 insertions(+)
create mode 100644 llvm/test/CodeGen/PowerPC/remove-redundant-li-skip-imp-kill.mir
diff --git llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp
index a4b4bf2973d..4ea714ff15f 100644
--- llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp
+++ llvm/lib/Target/PowerPC/PPCPreEmitPeephole.cpp
@@ -109,6 +109,16 @@ namespace {
// Track the operand that kill Reg. We would unset the kill flag of
// the operand if there is a following redundant load immediate.
int KillIdx = AfterBBI->findRegisterUseOperandIdx(Reg, true, TRI);
+
+ // We can't just clear implicit kills, so if we encounter one, stop
+ // looking further.
+ if (KillIdx != -1 && AfterBBI->getOperand(KillIdx).isImplicit()) {
+ LLVM_DEBUG(dbgs()
+ << "Encountered an implicit kill, cannot proceed: ");
+ LLVM_DEBUG(AfterBBI->dump());
+ break;
+ }
+
if (KillIdx != -1) {
assert(!DeadOrKillToUnset && "Shouldn't kill same register twice");
DeadOrKillToUnset = &AfterBBI->getOperand(KillIdx);
diff --git llvm/test/CodeGen/PowerPC/remove-redundant-li-skip-imp-kill.mir llvm/test/CodeGen/PowerPC/remove-redundant-li-skip-imp-kill.mir
new file mode 100644
index 00000000000..78091d027ce
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/remove-redundant-li-skip-imp-kill.mir
@@ -0,0 +1,114 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mcpu=pwr9 -mtriple=powerpc64le-unknown-unknown -run-pass \
+# RUN: ppc-pre-emit-peephole %s -o - | FileCheck %s
+--- |
+ ; ModuleID = 'a.ll'
+ source_filename = "a.ll"
+ target datalayout = "e-m:e-i64:64-n32:64"
+
+ ; Function Attrs: nounwind
+ define dso_local signext i32 @b(i32 signext %a, i32* nocapture %b) local_unnamed_addr #0 {
+ entry:
+ %call = tail call signext i32 @g(i32 signext %a)
+ store i32 %call, i32* %b, align 4
+ %call1 = tail call signext i32 @g(i32 signext %a)
+ ret i32 %call1
+ }
+
+ ; Function Attrs: nounwind
+ declare signext i32 @g(i32 signext) local_unnamed_addr #0
+
+ ; Function Attrs: nounwind
+ declare void @llvm.stackprotector(i8*, i8**) #0
+
+ attributes #0 = { nounwind }
+
+...
+---
+name: b
+alignment: 16
+exposesReturnsTwice: false
+legalized: false
+regBankSelected: false
+selected: false
+failedISel: false
+tracksRegLiveness: true
+hasWinCFI: false
+registers: []
+liveins:
+ - { reg: '$x3', virtual-reg: '' }
+ - { reg: '$x4', virtual-reg: '' }
+frameInfo:
+ isFrameAddressTaken: false
+ isReturnAddressTaken: false
+ hasStackMap: false
+ hasPatchPoint: false
+ stackSize: 64
+ offsetAdjustment: 0
+ maxAlignment: 1
+ adjustsStack: true
+ hasCalls: true
+ stackProtector: ''
+ maxCallFrameSize: 32
+ cvBytesOfCalleeSavedRegisters: 0
+ hasOpaqueSPAdjustment: false
+ hasVAStart: false
+ hasMustTailInVarArgFunc: false
+ localFrameSize: 0
+ savePoint: ''
+ restorePoint: ''
+fixedStack:
+ - { id: 0, type: spill-slot, offset: -80, size: 8, alignment: 16, stack-id: default,
+ callee-saved-register: '$x30', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+ - { id: 1, type: spill-slot, offset: -88, size: 8, alignment: 8, stack-id: default,
+ callee-saved-register: '$x29', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+stack: []
+callSites: []
+constants: []
+machineFunctionInfo: {}
+body: |
+ bb.0.entry:
+ liveins: $x3, $x4, $x29, $x30
+
+ ; CHECK-LABEL: name: b
+ ; CHECK: liveins: $x3, $x4, $x29, $x30
+ ; CHECK: $x0 = MFLR8 implicit $lr8
+ ; CHECK: STD killed $x29, -24, $x1 :: (store 8 into %fixed-stack.0)
+ ; CHECK: STD killed $x30, -16, $x1 :: (store 8 into %fixed-stack.1, align 16)
+ ; CHECK: STD killed $x0, 16, $x1
+ ; CHECK: $x1 = STDU $x1, -64, $x1
+ ; CHECK: $x30 = OR8 killed $x4, $x4
+ ; CHECK: dead $r4 = LI 10, implicit-def $x4
+ ; CHECK: $x29 = OR8 $x3, $x3
+ ; CHECK: BL8_NOP @g, csr_ppc64_r2_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit killed $x4, implicit $x2, implicit-def $r1, implicit-def $x3
+ ; CHECK: STW8 killed renamable $x3, 0, killed renamable $x30 :: (store 4 into %ir.b)
+ ; CHECK: $x3 = OR8 killed $x29, $x29
+ ; CHECK: BL8_NOP @g, csr_ppc64_r2_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def $x3
+ ; CHECK: $x1 = ADDI8 $x1, 64
+ ; CHECK: $x0 = LD 16, $x1
+ ; CHECK: $x30 = LD -16, $x1 :: (load 8 from %fixed-stack.1, align 16)
+ ; CHECK: $x29 = LD -24, $x1 :: (load 8 from %fixed-stack.0)
+ ; CHECK: MTLR8 killed $x0, implicit-def $lr8
+ ; CHECK: BLR8 implicit $lr8, implicit $rm, implicit killed $x3
+ $x0 = MFLR8 implicit $lr8
+ STD killed $x29, -24, $x1 :: (store 8 into %fixed-stack.1)
+ STD killed $x30, -16, $x1 :: (store 8 into %fixed-stack.0, align 16)
+ STD killed $x0, 16, $x1
+ $x1 = STDU $x1, -64, $x1
+ $x30 = OR8 killed $x4, $x4
+ dead $r4 = LI 10, implicit-def $x4
+ $x29 = OR8 $x3, $x3
+ BL8_NOP @g, csr_ppc64_r2_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit killed $x4, implicit $x2, implicit-def $r1, implicit-def $x3
+ STW8 killed renamable $x3, 0, killed renamable $x30 :: (store 4 into %ir.b)
+ $x3 = OR8 killed $x29, $x29
+ BL8_NOP @g, csr_ppc64_r2_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def $x3
+ $x1 = ADDI8 $x1, 64
+ $x0 = LD 16, $x1
+ $x30 = LD -16, $x1 :: (load 8 from %fixed-stack.0, align 16)
+ $x29 = LD -24, $x1 :: (load 8 from %fixed-stack.1)
+ MTLR8 killed $x0, implicit-def $lr8
+ BLR8 implicit $lr8, implicit $rm, implicit killed $x3
+
+...
--
2.26.0
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