[llvm] r219512 - [MiSched] Fix a logic error in tryPressure()

[Hal Finkel]

Author: hfinkel
Date: Fri Oct 10 12:06:20 2014
New Revision: 219512

URL: http://llvm.org/viewvc/llvm-project?rev=219512&view=rev
Log:
[MiSched] Fix a logic error in tryPressure()

Fixes a logic error in the MachineScheduler found by Steve Montgomery (and
confirmed by Andy). This has gone unfixed for months because the fix has been
found to introduce some small performance regressions. However, Andy has
recommended that, at this point, we fix this to avoid further dependence on the
incorrect behavior (and then follow-up separately on any regressions), and I
agree.

Fixes PR18883.

Modified:
    llvm/trunk/lib/CodeGen/MachineScheduler.cpp
    llvm/trunk/test/CodeGen/X86/misched-matmul.ll
    llvm/trunk/test/CodeGen/X86/ragreedy-last-chance-recoloring.ll

Modified: llvm/trunk/lib/CodeGen/MachineScheduler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineScheduler.cpp?rev=219512&r1=219511&r2=219512&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineScheduler.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineScheduler.cpp Fri Oct 10 12:06:20 2014
@@ -2495,8 +2495,8 @@ static bool tryPressure(const PressureCh
   }
   // If one candidate decreases and the other increases, go with it.
   // Invalid candidates have UnitInc==0.
-  if (tryLess(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand,
-              Reason)) {
+  if (tryGreater(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand,
+                 Reason)) {
     return true;
   }
   // If the candidates are decreasing pressure, reverse priority.

Modified: llvm/trunk/test/CodeGen/X86/misched-matmul.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/misched-matmul.ll?rev=219512&r1=219511&r2=219512&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/misched-matmul.ll (original)
+++ llvm/trunk/test/CodeGen/X86/misched-matmul.ll Fri Oct 10 12:06:20 2014
@@ -10,7 +10,7 @@
 ; more complex cases.
 ;
 ; CHECK: @wrap_mul4
-; CHECK: 22 regalloc - Number of spills inserted
+; CHECK: 23 regalloc - Number of spills inserted
 
 define void @wrap_mul4(double* nocapture %Out, [4 x double]* nocapture %A, [4 x double]* nocapture %B) #0 {
 entry:

Modified: llvm/trunk/test/CodeGen/X86/ragreedy-last-chance-recoloring.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/ragreedy-last-chance-recoloring.ll?rev=219512&r1=219511&r2=219512&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/ragreedy-last-chance-recoloring.ll (original)
+++ llvm/trunk/test/CodeGen/X86/ragreedy-last-chance-recoloring.ll Fri Oct 10 12:06:20 2014
@@ -2,10 +2,12 @@
 ; Without the last chance recoloring, this test fails with:
 ; "ran out of registers".
 
-; RUN: not llc -regalloc=greedy -relocation-model=pic -lcr-max-depth=0  < %s 2>&1 | FileCheck %s --check-prefix=CHECK-DEPTH
+; NOTE: With the fix to PR18883, we don't actually run out of registers here
+; any more, and so those checks are disabled. This test remains only for general coverage.
+; XXX: not llc -regalloc=greedy -relocation-model=pic -lcr-max-depth=0  < %s 2>&1 | FileCheck %s --check-prefix=CHECK-DEPTH
 ; Test whether failure due to cutoff for depth is reported
 
-; RUN: not llc -regalloc=greedy -relocation-model=pic -lcr-max-interf=1  < %s 2>&1 | FileCheck %s --check-prefix=CHECK-INTERF
+; XXX: not llc -regalloc=greedy -relocation-model=pic -lcr-max-interf=1  < %s 2>&1 | FileCheck %s --check-prefix=CHECK-INTERF
 ; Test whether failure due to cutoff for interference is reported
 
 ; RUN: llc -regalloc=greedy -relocation-model=pic -lcr-max-interf=1 -lcr-max-depth=0 -exhaustive-register-search < %s > %t 2>&1