[CodeGen] Combine two loops in SlotIndexes.cpp file (#127631)

Merged two loops that were iterating over the same machine basic block
into one, also did some minor readability improvements (variable
renaming, commenting and absorbing if condition into a variable)

Author: Rifet-c

llvm/lib/CodeGen/SlotIndexes.cpp

@@ -212,6 +212,7 @@ void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
   IndexList::iterator ListI = endIdx.listEntry()->getIterator();
   MachineBasicBlock::iterator MBBI = End;
   bool pastStart = false;
+  bool OldIndexesRemoved = false;
   while (ListI != ListB || MBBI != Begin || (includeStart && !pastStart)) {
     assert(ListI->getIndex() >= startIdx.getIndex() &&
            (includeStart || !pastStart) &&
@@ -220,32 +221,40 @@ void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
     MachineInstr *SlotMI = ListI->getInstr();
     MachineInstr *MI = (MBBI != MBB->end() && !pastStart) ? &*MBBI : nullptr;
     bool MBBIAtBegin = MBBI == Begin && (!includeStart || pastStart);
+    bool MIIndexNotFound = MI && !mi2iMap.contains(MI);
+    bool SlotMIRemoved = false;
 
     if (SlotMI == MI && !MBBIAtBegin) {
       --ListI;
       if (MBBI != Begin)
         --MBBI;
       else
         pastStart = true;
-    } else if (MI && !mi2iMap.contains(MI)) {
+    } else if (MIIndexNotFound || OldIndexesRemoved) {
       if (MBBI != Begin)
         --MBBI;
       else
         pastStart = true;
     } else {
-      --ListI;
-      if (SlotMI)
+      // We ran through all the indexes on the interval
+      //   -> The only thing left is to go through all the
+      //   remaining MBB instructions and update their indexes
+      if (ListI == ListB)
+        OldIndexesRemoved = true;
+      else
+        --ListI;
+      if (SlotMI) {
         removeMachineInstrFromMaps(*SlotMI);
+        SlotMIRemoved = true;
+      }
     }
-  }
 
-  // In theory this could be combined with the previous loop, but it is tricky
-  // to update the IndexList while we are iterating it.
-  for (MachineBasicBlock::iterator I = End; I != Begin;) {
-    --I;
-    MachineInstr &MI = *I;
-    if (!MI.isDebugOrPseudoInstr() && !mi2iMap.contains(&MI))
-      insertMachineInstrInMaps(MI);
+    MachineInstr *InstrToInsert = SlotMIRemoved ? SlotMI : MI;
+
+    // Insert instruction back into the maps after passing it/removing the index
+    if ((MIIndexNotFound || SlotMIRemoved) && InstrToInsert->getParent() &&
+        !InstrToInsert->isDebugOrPseudoInstr())
+      insertMachineInstrInMaps(*InstrToInsert);
   }
 }
 

llvm/test/CodeGen/Thumb2/mve-shuffle.ll

@@ -223,18 +223,31 @@ entry:
 }
 
 define arm_aapcs_vfpcc <8 x i16> @shuffle3_i16(<8 x i16> %src) {
-; CHECK-LABEL: shuffle3_i16:
-; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    vmovx.f16 s5, s3
-; CHECK-NEXT:    vmovx.f16 s6, s1
-; CHECK-NEXT:    vmovx.f16 s4, s0
-; CHECK-NEXT:    vins.f16 s1, s0
-; CHECK-NEXT:    vins.f16 s6, s4
-; CHECK-NEXT:    vins.f16 s5, s3
-; CHECK-NEXT:    vmov.f32 s4, s2
-; CHECK-NEXT:    vmov.f32 s7, s1
-; CHECK-NEXT:    vmov q0, q1
-; CHECK-NEXT:    bx lr
+; CHECK-LV-LABEL: shuffle3_i16:
+; CHECK-LV:       @ %bb.0: @ %entry
+; CHECK-LV-NEXT:    vmovx.f16 s5, s3
+; CHECK-LV-NEXT:    vmovx.f16 s6, s1
+; CHECK-LV-NEXT:    vmovx.f16 s4, s0
+; CHECK-LV-NEXT:    vins.f16 s1, s0
+; CHECK-LV-NEXT:    vins.f16 s6, s4
+; CHECK-LV-NEXT:    vins.f16 s5, s3
+; CHECK-LV-NEXT:    vmov.f32 s4, s2
+; CHECK-LV-NEXT:    vmov.f32 s7, s1
+; CHECK-LV-NEXT:    vmov q0, q1
+; CHECK-LV-NEXT:    bx lr
+
+; CHECK-LIS-LABEL: shuffle3_i16:
+; CHECK-LIS:       @ %bb.0: @ %entry
+; CHECK-LIS-NEXT:    vmov q1, q0
+; CHECK-LIS-NEXT:    vmovx.f16 s2, s5
+; CHECK-LIS-NEXT:    vmovx.f16 s0, s4
+; CHECK-LIS-NEXT:    vins.f16 s5, s4
+; CHECK-LIS-NEXT:    vins.f16 s2, s0
+; CHECK-LIS-NEXT:    vmov.f32 s0, s6
+; CHECK-LIS-NEXT:    vmovx.f16 s1, s7
+; CHECK-LIS-NEXT:    vmov.f32 s3, s5
+; CHECK-LIS-NEXT:    vins.f16 s1, s7
+; CHECK-LIS-NEXT:    bx lr
 entry:
   %out = shufflevector <8 x i16> %src, <8 x i16> undef, <8 x i32> <i32 4, i32 5, i32 7, i32 6, i32 3, i32 1, i32 2, i32 0>
   ret <8 x i16> %out
@@ -1145,18 +1158,31 @@ entry:
 }
 
 define arm_aapcs_vfpcc <8 x half> @shuffle3_f16(<8 x half> %src) {
-; CHECK-LABEL: shuffle3_f16:
-; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    vmovx.f16 s5, s3
-; CHECK-NEXT:    vmovx.f16 s6, s1
-; CHECK-NEXT:    vmovx.f16 s4, s0
-; CHECK-NEXT:    vins.f16 s1, s0
-; CHECK-NEXT:    vins.f16 s6, s4
-; CHECK-NEXT:    vins.f16 s5, s3
-; CHECK-NEXT:    vmov.f32 s4, s2
-; CHECK-NEXT:    vmov.f32 s7, s1
-; CHECK-NEXT:    vmov q0, q1
-; CHECK-NEXT:    bx lr
+; CHECK-LV-LABEL: shuffle3_f16:
+; CHECK-LV:       @ %bb.0: @ %entry
+; CHECK-LV-NEXT:    vmovx.f16 s5, s3
+; CHECK-LV-NEXT:    vmovx.f16 s6, s1
+; CHECK-LV-NEXT:    vmovx.f16 s4, s0
+; CHECK-LV-NEXT:    vins.f16 s1, s0
+; CHECK-LV-NEXT:    vins.f16 s6, s4
+; CHECK-LV-NEXT:    vins.f16 s5, s3
+; CHECK-LV-NEXT:    vmov.f32 s4, s2
+; CHECK-LV-NEXT:    vmov.f32 s7, s1
+; CHECK-LV-NEXT:    vmov q0, q1
+; CHECK-LV-NEXT:    bx lr
+
+; CHECK-LIS-LABEL: shuffle3_f16:
+; CHECK-LIS:       @ %bb.0: @ %entry
+; CHECK-LIS-NEXT:    vmov q1, q0
+; CHECK-LIS-NEXT:    vmovx.f16 s2, s5
+; CHECK-LIS-NEXT:    vmovx.f16 s0, s4
+; CHECK-LIS-NEXT:    vins.f16 s5, s4
+; CHECK-LIS-NEXT:    vins.f16 s2, s0
+; CHECK-LIS-NEXT:    vmov.f32 s0, s6
+; CHECK-LIS-NEXT:    vmovx.f16 s1, s7
+; CHECK-LIS-NEXT:    vmov.f32 s3, s5
+; CHECK-LIS-NEXT:    vins.f16 s1, s7
+; CHECK-LIS-NEXT:    bx lr
 entry:
   %out = shufflevector <8 x half> %src, <8 x half> undef, <8 x i32> <i32 4, i32 5, i32 7, i32 6, i32 3, i32 1, i32 2, i32 0>
   ret <8 x half> %out
@@ -1467,27 +1493,47 @@ entry:
   ret <2 x double> %out
 }
 define arm_aapcs_vfpcc <8 x double> @shuffle9_f64(<4 x double> %src1, <4 x double> %src2) {
-; CHECK-LABEL: shuffle9_f64:
-; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    .vsave {d8, d9, d10, d11}
-; CHECK-NEXT:    vpush {d8, d9, d10, d11}
-; CHECK-NEXT:    vmov q5, q2
-; CHECK-NEXT:    vmov.f32 s16, s0
-; CHECK-NEXT:    vmov.f32 s18, s20
-; CHECK-NEXT:    vmov.f32 s20, s2
-; CHECK-NEXT:    vmov.f32 s10, s12
-; CHECK-NEXT:    vmov.f32 s19, s21
-; CHECK-NEXT:    vmov.f32 s8, s4
-; CHECK-NEXT:    vmov.f32 s17, s1
-; CHECK-NEXT:    vmov.f32 s21, s3
-; CHECK-NEXT:    vmov q0, q4
-; CHECK-NEXT:    vmov.f32 s12, s6
-; CHECK-NEXT:    vmov.f32 s11, s13
-; CHECK-NEXT:    vmov.f32 s9, s5
-; CHECK-NEXT:    vmov.f32 s13, s7
-; CHECK-NEXT:    vmov q1, q5
-; CHECK-NEXT:    vpop {d8, d9, d10, d11}
-; CHECK-NEXT:    bx lr
+; CHECK-LV-LABEL: shuffle9_f64:
+; CHECK-LV:       @ %bb.0: @ %entry
+; CHECK-LV-NEXT:    .vsave {d8, d9, d10, d11}
+; CHECK-LV-NEXT:    vpush {d8, d9, d10, d11}
+; CHECK-LV-NEXT:    vmov q5, q2
+; CHECK-LV-NEXT:    vmov.f32 s16, s0
+; CHECK-LV-NEXT:    vmov.f32 s18, s20
+; CHECK-LV-NEXT:    vmov.f32 s20, s2
+; CHECK-LV-NEXT:    vmov.f32 s10, s12
+; CHECK-LV-NEXT:    vmov.f32 s19, s21
+; CHECK-LV-NEXT:    vmov.f32 s8, s4
+; CHECK-LV-NEXT:    vmov.f32 s17, s1
+; CHECK-LV-NEXT:    vmov.f32 s21, s3
+; CHECK-LV-NEXT:    vmov q0, q4
+; CHECK-LV-NEXT:    vmov.f32 s12, s6
+; CHECK-LV-NEXT:    vmov.f32 s11, s13
+; CHECK-LV-NEXT:    vmov.f32 s9, s5
+; CHECK-LV-NEXT:    vmov.f32 s13, s7
+; CHECK-LV-NEXT:    vmov q1, q5
+; CHECK-LV-NEXT:    vpop {d8, d9, d10, d11}
+; CHECK-LV-NEXT:    bx lr
+
+; CHECK-LIS-LABEL: shuffle9_f64:
+; CHECK-LIS:       @ %bb.0: @ %entry
+; CHECK-LIS-NEXT:    .vsave {d8, d9, d10, d11}
+; CHECK-LIS-NEXT:    vpush {d8, d9, d10, d11}
+; CHECK-LIS-NEXT:    vmov q5, q2
+; CHECK-LIS-NEXT:    vmov q4, q0
+; CHECK-LIS-NEXT:    vmov.f32 s2, s20
+; CHECK-LIS-NEXT:    vmov.f32 s20, s18
+; CHECK-LIS-NEXT:    vmov.f32 s10, s12
+; CHECK-LIS-NEXT:    vmov.f32 s3, s21
+; CHECK-LIS-NEXT:    vmov.f32 s8, s4
+; CHECK-LIS-NEXT:    vmov.f32 s21, s19
+; CHECK-LIS-NEXT:    vmov.f32 s12, s6
+; CHECK-LIS-NEXT:    vmov.f32 s11, s13
+; CHECK-LIS-NEXT:    vmov.f32 s9, s5
+; CHECK-LIS-NEXT:    vmov.f32 s13, s7
+; CHECK-LIS-NEXT:    vmov q1, q5
+; CHECK-LIS-NEXT:    vpop {d8, d9, d10, d11}
+; CHECK-LIS-NEXT:    bx lr
 entry:
   %out = shufflevector <4 x double> %src1, <4 x double> %src2, <8 x i32> <i32 0, i32 4, i32 1, i32 5, i32 2, i32 6, i32 3, i32 7>
   ret <8 x double> %out
@@ -1560,27 +1606,47 @@ entry:
   ret <2 x i64> %out
 }
 define arm_aapcs_vfpcc <8 x i64> @shuffle9_i64(<4 x i64> %src1, <4 x i64> %src2) {
-; CHECK-LABEL: shuffle9_i64:
-; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    .vsave {d8, d9, d10, d11}
-; CHECK-NEXT:    vpush {d8, d9, d10, d11}
-; CHECK-NEXT:    vmov q5, q2
-; CHECK-NEXT:    vmov.f32 s16, s0
-; CHECK-NEXT:    vmov.f32 s18, s20
-; CHECK-NEXT:    vmov.f32 s20, s2
-; CHECK-NEXT:    vmov.f32 s10, s12
-; CHECK-NEXT:    vmov.f32 s19, s21
-; CHECK-NEXT:    vmov.f32 s8, s4
-; CHECK-NEXT:    vmov.f32 s17, s1
-; CHECK-NEXT:    vmov.f32 s21, s3
-; CHECK-NEXT:    vmov q0, q4
-; CHECK-NEXT:    vmov.f32 s12, s6
-; CHECK-NEXT:    vmov.f32 s11, s13
-; CHECK-NEXT:    vmov.f32 s9, s5
-; CHECK-NEXT:    vmov.f32 s13, s7
-; CHECK-NEXT:    vmov q1, q5
-; CHECK-NEXT:    vpop {d8, d9, d10, d11}
-; CHECK-NEXT:    bx lr
+; CHECK-LV-LABEL: shuffle9_i64:
+; CHECK-LV:       @ %bb.0: @ %entry
+; CHECK-LV-NEXT:    .vsave {d8, d9, d10, d11}
+; CHECK-LV-NEXT:    vpush {d8, d9, d10, d11}
+; CHECK-LV-NEXT:    vmov q5, q2
+; CHECK-LV-NEXT:    vmov.f32 s16, s0
+; CHECK-LV-NEXT:    vmov.f32 s18, s20
+; CHECK-LV-NEXT:    vmov.f32 s20, s2
+; CHECK-LV-NEXT:    vmov.f32 s10, s12
+; CHECK-LV-NEXT:    vmov.f32 s19, s21
+; CHECK-LV-NEXT:    vmov.f32 s8, s4
+; CHECK-LV-NEXT:    vmov.f32 s17, s1
+; CHECK-LV-NEXT:    vmov.f32 s21, s3
+; CHECK-LV-NEXT:    vmov q0, q4
+; CHECK-LV-NEXT:    vmov.f32 s12, s6
+; CHECK-LV-NEXT:    vmov.f32 s11, s13
+; CHECK-LV-NEXT:    vmov.f32 s9, s5
+; CHECK-LV-NEXT:    vmov.f32 s13, s7
+; CHECK-LV-NEXT:    vmov q1, q5
+; CHECK-LV-NEXT:    vpop {d8, d9, d10, d11}
+; CHECK-LV-NEXT:    bx lr
+
+; CHECK-LIS-LABEL: shuffle9_i64:
+; CHECK-LIS:       @ %bb.0: @ %entry
+; CHECK-LIS-NEXT:    .vsave {d8, d9, d10, d11}
+; CHECK-LIS-NEXT:    vpush {d8, d9, d10, d11}
+; CHECK-LIS-NEXT:    vmov q5, q2
+; CHECK-LIS-NEXT:    vmov q4, q0
+; CHECK-LIS-NEXT:    vmov.f32 s2, s20
+; CHECK-LIS-NEXT:    vmov.f32 s20, s18
+; CHECK-LIS-NEXT:    vmov.f32 s10, s12
+; CHECK-LIS-NEXT:    vmov.f32 s3, s21
+; CHECK-LIS-NEXT:    vmov.f32 s8, s4
+; CHECK-LIS-NEXT:    vmov.f32 s21, s19
+; CHECK-LIS-NEXT:    vmov.f32 s12, s6
+; CHECK-LIS-NEXT:    vmov.f32 s11, s13
+; CHECK-LIS-NEXT:    vmov.f32 s9, s5
+; CHECK-LIS-NEXT:    vmov.f32 s13, s7
+; CHECK-LIS-NEXT:    vmov q1, q5
+; CHECK-LIS-NEXT:    vpop {d8, d9, d10, d11}
+; CHECK-LIS-NEXT:    bx lr
 entry:
   %out = shufflevector <4 x i64> %src1, <4 x i64> %src2, <8 x i32> <i32 0, i32 4, i32 1, i32 5, i32 2, i32 6, i32 3, i32 7>
   ret <8 x i64> %out