[PATCH] D110829: [X86] Special-case ADD of two identical registers in convertToThreeAddress

[Jay Foad via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG5b8befdd026d: [X86] Special-case ADD of two identical registers in convertToThreeAddress (authored by foad).

Changed prior to commit:
  https://reviews.llvm.org/D110829?vs=377297&id=377935#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110829/new/

https://reviews.llvm.org/D110829

Files:
  llvm/lib/Target/X86/X86InstrInfo.cpp
  llvm/test/CodeGen/X86/twoaddr-mul2.mir


Index: llvm/test/CodeGen/X86/twoaddr-mul2.mir
===================================================================
--- llvm/test/CodeGen/X86/twoaddr-mul2.mir
+++ llvm/test/CodeGen/X86/twoaddr-mul2.mir
@@ -1,7 +1,7 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-# RUN: llc -mtriple=x86_64-unknown -mcpu=haswell -run-pass=twoaddressinstruction %s -o - | FileCheck %s
+# RUN: llc -mtriple=x86_64-unknown -mcpu=haswell -run-pass=twoaddressinstruction -verify-machineinstrs %s -o - | FileCheck %s
 
-# FIXME: The killed flag should be on the second COPY from [[COPY]], not the first one.
+# Check that we don't have any uses of [[COPY]] after it is killed.
 ---
 name: test_mul_by_2
 tracksRegLiveness: true
@@ -13,9 +13,8 @@
     ; CHECK: liveins: $edi
     ; CHECK-NEXT: {{  $}}
     ; CHECK-NEXT: [[COPY:%[0-9]+]]:gr32 = COPY killed $edi
-    ; CHECK-NEXT: undef %2.sub_32bit:gr64 = COPY killed [[COPY]]
-    ; CHECK-NEXT: undef %3.sub_32bit:gr64_nosp = COPY [[COPY]]
-    ; CHECK-NEXT: [[LEA64_32r:%[0-9]+]]:gr32 = LEA64_32r killed %2, 1, killed %3, 0, $noreg
+    ; CHECK-NEXT: undef %2.sub_32bit:gr64_nosp = COPY killed [[COPY]]
+    ; CHECK-NEXT: [[LEA64_32r:%[0-9]+]]:gr32 = LEA64_32r killed %2, 1, killed %2, 0, $noreg
     ; CHECK-NEXT: $eax = COPY killed [[LEA64_32r]]
     ; CHECK-NEXT: RET 0, killed $eax
     %0:gr32 = COPY killed $edi
Index: llvm/lib/Target/X86/X86InstrInfo.cpp
===================================================================
--- llvm/lib/Target/X86/X86InstrInfo.cpp
+++ llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -1205,12 +1205,12 @@
       &X86::GR64_NOSPRegClass : &X86::GR32_NOSPRegClass;
   }
   Register SrcReg = Src.getReg();
+  isKill = MI.killsRegister(SrcReg);
 
   // For both LEA64 and LEA32 the register already has essentially the right
   // type (32-bit or 64-bit) we may just need to forbid SP.
   if (Opc != X86::LEA64_32r) {
     NewSrc = SrcReg;
-    isKill = Src.isKill();
     assert(!Src.isUndef() && "Undef op doesn't need optimization");
 
     if (NewSrc.isVirtual() && !MF.getRegInfo().constrainRegClass(NewSrc, RC))
@@ -1225,8 +1225,7 @@
     ImplicitOp = Src;
     ImplicitOp.setImplicit();
 
-    NewSrc = getX86SubSuperRegister(Src.getReg(), 64);
-    isKill = Src.isKill();
+    NewSrc = getX86SubSuperRegister(SrcReg, 64);
     assert(!Src.isUndef() && "Undef op doesn't need optimization");
   } else {
     // Virtual register of the wrong class, we have to create a temporary 64-bit
@@ -1235,7 +1234,7 @@
     MachineInstr *Copy =
         BuildMI(*MI.getParent(), MI, MI.getDebugLoc(), get(TargetOpcode::COPY))
             .addReg(NewSrc, RegState::Define | RegState::Undef, X86::sub_32bit)
-            .add(Src);
+            .addReg(SrcReg, getKillRegState(isKill));
 
     // Which is obviously going to be dead after we're done with it.
     isKill = true;
@@ -1532,13 +1531,6 @@
     else
       Opc = Is64Bit ? X86::LEA64_32r : X86::LEA32r;
 
-    bool isKill;
-    Register SrcReg;
-    MachineOperand ImplicitOp = MachineOperand::CreateReg(0, false);
-    if (!classifyLEAReg(MI, Src, Opc, /*AllowSP=*/ true,
-                        SrcReg, isKill, ImplicitOp, LV))
-      return nullptr;
-
     const MachineOperand &Src2 = MI.getOperand(2);
     bool isKill2;
     Register SrcReg2;
@@ -1547,6 +1539,20 @@
                         SrcReg2, isKill2, ImplicitOp2, LV))
       return nullptr;
 
+    bool isKill;
+    Register SrcReg;
+    MachineOperand ImplicitOp = MachineOperand::CreateReg(0, false);
+    if (Src.getReg() == Src2.getReg()) {
+      // Don't call classify LEAReg a second time on the same register, in case
+      // the first call inserted a COPY from Src2 and marked it as killed.
+      isKill = isKill2;
+      SrcReg = SrcReg2;
+    } else {
+      if (!classifyLEAReg(MI, Src, Opc, /*AllowSP=*/true,
+                          SrcReg, isKill, ImplicitOp, LV))
+        return nullptr;
+    }
+
     MachineInstrBuilder MIB = BuildMI(MF, MI.getDebugLoc(), get(Opc)).add(Dest);
     if (ImplicitOp.getReg() != 0)
       MIB.add(ImplicitOp);


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