Fix two remaining issue after fixing PR15355 when CMOV is not available

- Phi nodes should be replaced/updated after lowering CMOV into branch
  because 'mainMBB' updating operand in Phi node is changed.
- Add EFLAGS in livein before lowering the 2nd CMOV. It's necessary as
  we will reuse the EFLAGS generated before the 1st lowered CMOV, which
  won't clobber EFLAGS. However, we need explicitly specify that.
- '-attr=-cmov' test case are added.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176598 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86ISelLowering.cpp

@@ -13001,8 +13001,8 @@ X86TargetLowering::EmitAtomicLoadArith(MachineInstr *MI,
   MachineBasicBlock *origMainMBB = mainMBB;
 
   // Add a PHI.
-  BuildMI(mainMBB, DL, TII->get(X86::PHI), t4)
+  MachineInstr *Phi = BuildMI(mainMBB, DL, TII->get(X86::PHI), t4)
-    .addReg(t1).addMBB(thisMBB).addReg(t3).addMBB(mainMBB);
+                        .addReg(t1).addMBB(thisMBB).addReg(t3).addMBB(mainMBB);
 
   unsigned Opc = MI->getOpcode();
   switch (Opc) {
@@ -13105,6 +13105,11 @@ X86TargetLowering::EmitAtomicLoadArith(MachineInstr *MI,
               .addReg(SrcReg).addReg(t4)
               .addImm(CC);
       mainMBB = EmitLoweredSelect(MIB, mainMBB);
+      // Replace the original PHI node as mainMBB is changed after CMOV
+      // lowering.
+      BuildMI(*origMainMBB, Phi, DL, TII->get(X86::PHI), t4)
+        .addReg(t1).addMBB(thisMBB).addReg(t3).addMBB(mainMBB);
+      Phi->eraseFromParent();
     }
     break;
   }
@@ -13298,10 +13303,10 @@ X86TargetLowering::EmitAtomicLoadArith6432(MachineInstr *MI,
   MachineBasicBlock *origMainMBB = mainMBB;
 
   // Add PHIs.
-  BuildMI(mainMBB, DL, TII->get(X86::PHI), t4L)
+  MachineInstr *PhiL = BuildMI(mainMBB, DL, TII->get(X86::PHI), t4L)
-    .addReg(t1L).addMBB(thisMBB).addReg(t3L).addMBB(mainMBB);
+                        .addReg(t1L).addMBB(thisMBB).addReg(t3L).addMBB(mainMBB);
-  BuildMI(mainMBB, DL, TII->get(X86::PHI), t4H)
+  MachineInstr *PhiH = BuildMI(mainMBB, DL, TII->get(X86::PHI), t4H)
-    .addReg(t1H).addMBB(thisMBB).addReg(t3H).addMBB(mainMBB);
+                        .addReg(t1H).addMBB(thisMBB).addReg(t3H).addMBB(mainMBB);
 
   unsigned Opc = MI->getOpcode();
   switch (Opc) {
@@ -13375,10 +13380,21 @@ X86TargetLowering::EmitAtomicLoadArith6432(MachineInstr *MI,
               .addReg(SrcLoReg).addReg(t4L)
               .addImm(X86::COND_NE);
       mainMBB = EmitLoweredSelect(MIB, mainMBB);
+      // As the lowered CMOV won't clobber EFLAGS, we could reuse it for the
+      // 2nd CMOV lowering.
+      mainMBB->addLiveIn(X86::EFLAGS);
       MIB = BuildMI(mainMBB, DL, TII->get(X86::CMOV_GR32), t2H)
               .addReg(SrcHiReg).addReg(t4H)
               .addImm(X86::COND_NE);
       mainMBB = EmitLoweredSelect(MIB, mainMBB);
+      // Replace the original PHI node as mainMBB is changed after CMOV
+      // lowering.
+      BuildMI(*origMainMBB, PhiL, DL, TII->get(X86::PHI), t4L)
+        .addReg(t1L).addMBB(thisMBB).addReg(t3L).addMBB(mainMBB);
+      BuildMI(*origMainMBB, PhiH, DL, TII->get(X86::PHI), t4H)
+        .addReg(t1H).addMBB(thisMBB).addReg(t3H).addMBB(mainMBB);
+      PhiL->eraseFromParent();
+      PhiH->eraseFromParent();
     }
     break;
   }

test/CodeGen/X86/atomic-minmax-i6432.ll

@@ -1,4 +1,5 @@
 ; RUN: llc -march=x86 -mattr=+cmov -mtriple=i386-pc-linux -verify-machineinstrs < %s | FileCheck %s -check-prefix=LINUX
+; RUN: llc -march=x86 -mattr=-cmov -mtriple=i386-pc-linux -verify-machineinstrs < %s | FileCheck %s -check-prefix=NOCMOV
 ; RUN: llc -march=x86 -mtriple=i386-macosx -relocation-model=pic -verify-machineinstrs < %s | FileCheck %s -check-prefix=PIC
 
 @sc64 = external global i64
@@ -16,6 +17,16 @@ define void @atomic_maxmin_i6432() {
 ; LINUX: lock
 ; LINUX-NEXT: cmpxchg8b
 ; LINUX: jne [[LABEL]]
+; NOCMOV: [[LABEL:.LBB[0-9]+_[0-9]+]]
+; NOCMOV: cmpl
+; NOCMOV: setl
+; NOCMOV: cmpl
+; NOCMOV: setl
+; NOCMOV: jne
+; NOCMOV: jne
+; NOCMOV: lock
+; NOCMOV-NEXT: cmpxchg8b
+; NOCMOV: jne [[LABEL]]
   %2 = atomicrmw min  i64* @sc64, i64 6 acquire
 ; LINUX: [[LABEL:.LBB[0-9]+_[0-9]+]]
 ; LINUX: cmpl
@@ -27,6 +38,16 @@ define void @atomic_maxmin_i6432() {
 ; LINUX: lock
 ; LINUX-NEXT: cmpxchg8b
 ; LINUX: jne [[LABEL]]
+; NOCMOV: [[LABEL:.LBB[0-9]+_[0-9]+]]
+; NOCMOV: cmpl
+; NOCMOV: setg
+; NOCMOV: cmpl
+; NOCMOV: setg
+; NOCMOV: jne
+; NOCMOV: jne
+; NOCMOV: lock
+; NOCMOV-NEXT: cmpxchg8b
+; NOCMOV: jne [[LABEL]]
   %3 = atomicrmw umax i64* @sc64, i64 7 acquire
 ; LINUX: [[LABEL:.LBB[0-9]+_[0-9]+]]
 ; LINUX: cmpl
@@ -38,6 +59,16 @@ define void @atomic_maxmin_i6432() {
 ; LINUX: lock
 ; LINUX-NEXT: cmpxchg8b
 ; LINUX: jne [[LABEL]]
+; NOCMOV: [[LABEL:.LBB[0-9]+_[0-9]+]]
+; NOCMOV: cmpl
+; NOCMOV: setb
+; NOCMOV: cmpl
+; NOCMOV: setb
+; NOCMOV: jne
+; NOCMOV: jne
+; NOCMOV: lock
+; NOCMOV-NEXT: cmpxchg8b
+; NOCMOV: jne [[LABEL]]
   %4 = atomicrmw umin i64* @sc64, i64 8 acquire
 ; LINUX: [[LABEL:.LBB[0-9]+_[0-9]+]]
 ; LINUX: cmpl
@@ -49,6 +80,16 @@ define void @atomic_maxmin_i6432() {
 ; LINUX: lock
 ; LINUX-NEXT: cmpxchg8b
 ; LINUX: jne [[LABEL]]
+; NOCMOV: [[LABEL:.LBB[0-9]+_[0-9]+]]
+; NOCMOV: cmpl
+; NOCMOV: seta
+; NOCMOV: cmpl
+; NOCMOV: seta
+; NOCMOV: jne
+; NOCMOV: jne
+; NOCMOV: lock
+; NOCMOV-NEXT: cmpxchg8b
+; NOCMOV: jne [[LABEL]]
   ret void
 }
 

test/CodeGen/X86/atomic32.ll

@@ -1,5 +1,6 @@
 ; RUN: llc < %s -O0 -march=x86-64 -mcpu=corei7 -verify-machineinstrs | FileCheck %s --check-prefix X64
 ; RUN: llc < %s -O0 -march=x86 -mcpu=corei7 -verify-machineinstrs | FileCheck %s --check-prefix X32
+; RUN: llc < %s -O0 -march=x86 -mcpu=corei7 -mattr=-cmov -verify-machineinstrs | FileCheck %s --check-prefix NOCMOV
 
 @sc32 = external global i32
 
@@ -164,9 +165,15 @@ define void @atomic_fetch_max32(i32 %x) nounwind {
 ; X32:       cmov
 ; X32:       lock
 ; X32:       cmpxchgl
+
+; NOCMOV:    cmpl
+; NOCMOV:    jl
+; NOCMOV:    lock
+; NOCMOV:    cmpxchgl
   ret void
 ; X64:       ret
 ; X32:       ret
+; NOCMOV:    ret
 }
 
 define void @atomic_fetch_min32(i32 %x) nounwind {
@@ -180,9 +187,15 @@ define void @atomic_fetch_min32(i32 %x) nounwind {
 ; X32:       cmov
 ; X32:       lock
 ; X32:       cmpxchgl
+
+; NOCMOV:    cmpl
+; NOCMOV:    jg
+; NOCMOV:    lock
+; NOCMOV:    cmpxchgl
   ret void
 ; X64:       ret
 ; X32:       ret
+; NOCMOV:    ret
 }
 
 define void @atomic_fetch_umax32(i32 %x) nounwind {
@@ -196,9 +209,15 @@ define void @atomic_fetch_umax32(i32 %x) nounwind {
 ; X32:       cmov
 ; X32:       lock
 ; X32:       cmpxchgl
+
+; NOCMOV:    cmpl
+; NOCMOV:    jb
+; NOCMOV:    lock
+; NOCMOV:    cmpxchgl
   ret void
 ; X64:       ret
 ; X32:       ret
+; NOCMOV:    ret
 }
 
 define void @atomic_fetch_umin32(i32 %x) nounwind {
@@ -207,13 +226,20 @@ define void @atomic_fetch_umin32(i32 %x) nounwind {
 ; X64:       cmov
 ; X64:       lock
 ; X64:       cmpxchgl
+
 ; X32:       cmpl
 ; X32:       cmov
 ; X32:       lock
 ; X32:       cmpxchgl
+
+; NOCMOV:    cmpl
+; NOCMOV:    ja
+; NOCMOV:    lock
+; NOCMOV:    cmpxchgl
   ret void
 ; X64:       ret
 ; X32:       ret
+; NOCMOV:    ret
 }
 
 define void @atomic_fetch_cmpxchg32() nounwind {