[llvm] r282855 - Revert "[RegAllocGreedy] Attempt to split unspillable live intervals"

[Dylan McKay via llvm-commits]

Author: dylanmckay
Date: Fri Sep 30 09:05:15 2016
New Revision: 282855

URL: http://llvm.org/viewvc/llvm-project?rev=282855&view=rev
Log:
Revert "[RegAllocGreedy] Attempt to split unspillable live intervals"

It was accidentally committed.

Removed:
    llvm/trunk/test/CodeGen/AVR/high-pressure-on-ptrregs.ll
Modified:
    llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp

Modified: llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp?rev=282855&r1=282854&r2=282855&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp Fri Sep 30 09:05:15 2016
@@ -2556,20 +2556,18 @@ unsigned RAGreedy::selectOrSplitImpl(Liv
     return 0;
   }
 
-  if (Stage == RS_Split || Stage == RS_Split2) {
-    // Try splitting VirtReg or interferences.
-    unsigned NewVRegSizeBefore = NewVRegs.size();
-    unsigned PhysReg = trySplit(VirtReg, Order, NewVRegs);
-    if (PhysReg || (NewVRegs.size() - NewVRegSizeBefore))
-      return PhysReg;
-  }
-
   // If we couldn't allocate a register from spilling, there is probably some
   // invalid inline assembly. The base class wil report it.
   if (Stage >= RS_Done || !VirtReg.isSpillable())
     return tryLastChanceRecoloring(VirtReg, Order, NewVRegs, FixedRegisters,
                                    Depth);
 
+  // Try splitting VirtReg or interferences.
+  unsigned NewVRegSizeBefore = NewVRegs.size();
+  unsigned PhysReg = trySplit(VirtReg, Order, NewVRegs);
+  if (PhysReg || (NewVRegs.size() - NewVRegSizeBefore))
+    return PhysReg;
+
   // Finally spill VirtReg itself.
   if (EnableDeferredSpilling && getStage(VirtReg) < RS_Memory) {
     // TODO: This is experimental and in particular, we do not model

Removed: llvm/trunk/test/CodeGen/AVR/high-pressure-on-ptrregs.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AVR/high-pressure-on-ptrregs.ll?rev=282854&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/AVR/high-pressure-on-ptrregs.ll (original)
+++ llvm/trunk/test/CodeGen/AVR/high-pressure-on-ptrregs.ll (removed)
@@ -1,78 +0,0 @@
-; RUN: llc < %s -march=avr | FileCheck %s
-
-; This tests how LLVM handles IR which puts very high
-; presure on the PTRREGS class for the register allocator.
-;
-; This causes a problem because we only have one small register
-; class for loading and storing from pointers - 'PTRREGS'.
-; One of these registers is also used for the frame pointer, meaning
-; that we only ever have two registers available for these operations.
-;
-; There is an existing bug filed for this issue - PR14879.
-;
-; The specific failure:
-; LLVM ERROR: ran out of registers during register allocation
-;
-; It has been assembled from the following c code:
-;
-; struct ss
-; {
-;   int a;
-;   int b;
-;   int c;
-; };
-;
-; void loop(struct ss *x, struct ss **y, int z)
-; {
-;   int i;
-;   for (i=0; i<z; ++i)
-;   {
-;     x->c += y[i]->b;
-;   }
-; }
-
-%struct.ss = type { i16, i16, i16 }
-
-; CHECK-LABEL: loop
-define void @loop(%struct.ss* %x, %struct.ss** %y, i16 %z) {
-entry:
-  %x.addr = alloca %struct.ss*, align 2
-  %y.addr = alloca %struct.ss**, align 2
-  %z.addr = alloca i16, align 2
-  %i = alloca i16, align 2
-  store %struct.ss* %x, %struct.ss** %x.addr, align 2
-  store %struct.ss** %y, %struct.ss*** %y.addr, align 2
-  store i16 %z, i16* %z.addr, align 2
-  store i16 0, i16* %i, align 2
-  br label %for.cond
-
-for.cond:                                         ; preds = %for.inc, %entry
-  %0 = load i16, i16* %i, align 2
-  %1 = load i16, i16* %z.addr, align 2
-  %cmp = icmp slt i16 %0, %1
-  br i1 %cmp, label %for.body, label %for.end
-
-for.body:                                         ; preds = %for.cond
-  %2 = load i16, i16* %i, align 2
-  %3 = load %struct.ss**, %struct.ss*** %y.addr, align 2
-  %arrayidx = getelementptr inbounds %struct.ss*, %struct.ss** %3, i16 %2
-  %4 = load %struct.ss*, %struct.ss** %arrayidx, align 2
-  %b = getelementptr inbounds %struct.ss, %struct.ss* %4, i32 0, i32 1
-  %5 = load i16, i16* %b, align 2
-  %6 = load %struct.ss*, %struct.ss** %x.addr, align 2
-  %c = getelementptr inbounds %struct.ss, %struct.ss* %6, i32 0, i32 2
-  %7 = load i16, i16* %c, align 2
-  %add = add nsw i16 %7, %5
-  store i16 %add, i16* %c, align 2
-  br label %for.inc
-
-for.inc:                                          ; preds = %for.body
-  %8 = load i16, i16* %i, align 2
-  %inc = add nsw i16 %8, 1
-  store i16 %inc, i16* %i, align 2
-  br label %for.cond
-
-for.end:                                          ; preds = %for.cond
-  ret void
-}
-