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-rw-r--r--include/llvm/Target/TargetInstrInfo.h8
-rw-r--r--lib/CodeGen/StackSlotColoring.cpp11
-rw-r--r--lib/Target/SystemZ/SystemZInstrInfo.cpp25
-rw-r--r--lib/Target/SystemZ/SystemZInstrInfo.h2
-rw-r--r--test/CodeGen/SystemZ/spill-01.ll89
5 files changed, 134 insertions, 1 deletions
diff --git a/include/llvm/Target/TargetInstrInfo.h b/include/llvm/Target/TargetInstrInfo.h
index 7172eb0b68..f746daf921 100644
--- a/include/llvm/Target/TargetInstrInfo.h
+++ b/include/llvm/Target/TargetInstrInfo.h
@@ -173,6 +173,14 @@ public:
const MachineMemOperand *&MMO,
int &FrameIndex) const;
+ /// isStackSlotCopy - Return true if the specified machine instruction
+ /// is a copy of one stack slot to another and has no other effect.
+ /// Provide the identity of the two frame indices.
+ virtual bool isStackSlotCopy(const MachineInstr *MI, int &DestFrameIndex,
+ int &SrcFrameIndex) const {
+ return false;
+ }
+
/// reMaterialize - Re-issue the specified 'original' instruction at the
/// specific location targeting a new destination register.
/// The register in Orig->getOperand(0).getReg() will be substituted by
diff --git a/lib/CodeGen/StackSlotColoring.cpp b/lib/CodeGen/StackSlotColoring.cpp
index e1b63680e0..d0c9e1d677 100644
--- a/lib/CodeGen/StackSlotColoring.cpp
+++ b/lib/CodeGen/StackSlotColoring.cpp
@@ -377,10 +377,19 @@ bool StackSlotColoring::RemoveDeadStores(MachineBasicBlock* MBB) {
if (DCELimit != -1 && (int)NumDead >= DCELimit)
break;
+ int FirstSS, SecondSS;
+ if (TII->isStackSlotCopy(I, FirstSS, SecondSS) &&
+ FirstSS == SecondSS &&
+ FirstSS != -1) {
+ ++NumDead;
+ changed = true;
+ toErase.push_back(I);
+ continue;
+ }
+
MachineBasicBlock::iterator NextMI = llvm::next(I);
if (NextMI == MBB->end()) continue;
- int FirstSS, SecondSS;
unsigned LoadReg = 0;
unsigned StoreReg = 0;
if (!(LoadReg = TII->isLoadFromStackSlot(I, FirstSS))) continue;
diff --git a/lib/Target/SystemZ/SystemZInstrInfo.cpp b/lib/Target/SystemZ/SystemZInstrInfo.cpp
index 81d72e0574..cfd270ae43 100644
--- a/lib/Target/SystemZ/SystemZInstrInfo.cpp
+++ b/lib/Target/SystemZ/SystemZInstrInfo.cpp
@@ -104,6 +104,31 @@ unsigned SystemZInstrInfo::isStoreToStackSlot(const MachineInstr *MI,
return isSimpleMove(MI, FrameIndex, SystemZII::SimpleBDXStore);
}
+bool SystemZInstrInfo::isStackSlotCopy(const MachineInstr *MI,
+ int &DestFrameIndex,
+ int &SrcFrameIndex) const {
+ // Check for MVC 0(Length,FI1),0(FI2)
+ const MachineFrameInfo *MFI = MI->getParent()->getParent()->getFrameInfo();
+ if (MI->getOpcode() != SystemZ::MVC ||
+ !MI->getOperand(0).isFI() ||
+ MI->getOperand(1).getImm() != 0 ||
+ !MI->getOperand(3).isFI() ||
+ MI->getOperand(4).getImm() != 0)
+ return false;
+
+ // Check that Length covers the full slots.
+ int64_t Length = MI->getOperand(2).getImm();
+ unsigned FI1 = MI->getOperand(0).getIndex();
+ unsigned FI2 = MI->getOperand(3).getIndex();
+ if (MFI->getObjectSize(FI1) != Length ||
+ MFI->getObjectSize(FI2) != Length)
+ return false;
+
+ DestFrameIndex = FI1;
+ SrcFrameIndex = FI2;
+ return true;
+}
+
bool SystemZInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
diff --git a/lib/Target/SystemZ/SystemZInstrInfo.h b/lib/Target/SystemZ/SystemZInstrInfo.h
index 11d486cafb..3fe71d8854 100644
--- a/lib/Target/SystemZ/SystemZInstrInfo.h
+++ b/lib/Target/SystemZ/SystemZInstrInfo.h
@@ -91,6 +91,8 @@ public:
int &FrameIndex) const LLVM_OVERRIDE;
virtual unsigned isStoreToStackSlot(const MachineInstr *MI,
int &FrameIndex) const LLVM_OVERRIDE;
+ virtual bool isStackSlotCopy(const MachineInstr *MI, int &DestFrameIndex,
+ int &SrcFrameIndex) const LLVM_OVERRIDE;
virtual bool AnalyzeBranch(MachineBasicBlock &MBB,
MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
diff --git a/test/CodeGen/SystemZ/spill-01.ll b/test/CodeGen/SystemZ/spill-01.ll
index b2d9fe7be4..d48e9827f5 100644
--- a/test/CodeGen/SystemZ/spill-01.ll
+++ b/test/CodeGen/SystemZ/spill-01.ll
@@ -456,3 +456,92 @@ skip:
ret void
}
+
+; This used to generate a no-op MVC. It is very sensitive to spill heuristics.
+define void @f11() {
+; CHECK: f11:
+; CHECK-NOT: mvc [[OFFSET:[0-9]+]](8,%r15), [[OFFSET]](%r15)
+; CHECK: br %r14
+entry:
+ %val0 = load volatile i64 *@h0
+ %val1 = load volatile i64 *@h1
+ %val2 = load volatile i64 *@h2
+ %val3 = load volatile i64 *@h3
+ %val4 = load volatile i64 *@h4
+ %val5 = load volatile i64 *@h5
+ %val6 = load volatile i64 *@h6
+ %val7 = load volatile i64 *@h7
+
+ %altval0 = load volatile i64 *@h0
+ %altval1 = load volatile i64 *@h1
+
+ call void @foo()
+
+ store volatile i64 %val0, i64 *@h0
+ store volatile i64 %val1, i64 *@h1
+ store volatile i64 %val2, i64 *@h2
+ store volatile i64 %val3, i64 *@h3
+ store volatile i64 %val4, i64 *@h4
+ store volatile i64 %val5, i64 *@h5
+ store volatile i64 %val6, i64 *@h6
+ store volatile i64 %val7, i64 *@h7
+
+ %check = load volatile i64 *@h0
+ %cond = icmp eq i64 %check, 0
+ br i1 %cond, label %a1, label %b1
+
+a1:
+ call void @foo()
+ br label %join1
+
+b1:
+ call void @foo()
+ br label %join1
+
+join1:
+ %newval0 = phi i64 [ %val0, %a1 ], [ %altval0, %b1 ]
+
+ call void @foo()
+
+ store volatile i64 %val1, i64 *@h1
+ store volatile i64 %val2, i64 *@h2
+ store volatile i64 %val3, i64 *@h3
+ store volatile i64 %val4, i64 *@h4
+ store volatile i64 %val5, i64 *@h5
+ store volatile i64 %val6, i64 *@h6
+ store volatile i64 %val7, i64 *@h7
+ br i1 %cond, label %a2, label %b2
+
+a2:
+ call void @foo()
+ br label %join2
+
+b2:
+ call void @foo()
+ br label %join2
+
+join2:
+ %newval1 = phi i64 [ %val1, %a2 ], [ %altval1, %b2 ]
+
+ call void @foo()
+
+ store volatile i64 %val2, i64 *@h2
+ store volatile i64 %val3, i64 *@h3
+ store volatile i64 %val4, i64 *@h4
+ store volatile i64 %val5, i64 *@h5
+ store volatile i64 %val6, i64 *@h6
+ store volatile i64 %val7, i64 *@h7
+
+ call void @foo()
+
+ store volatile i64 %newval0, i64 *@h0
+ store volatile i64 %newval1, i64 *@h1
+ store volatile i64 %val2, i64 *@h2
+ store volatile i64 %val3, i64 *@h3
+ store volatile i64 %val4, i64 *@h4
+ store volatile i64 %val5, i64 *@h5
+ store volatile i64 %val6, i64 *@h6
+ store volatile i64 %val7, i64 *@h7
+
+ ret void
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-18 09:46:03 +0000