[llvm] 8f55fdf - [MacroFusion] Expose useful static methods. NFC.

[Joe Nash via llvm-commits]

Author: Joe Nash
Date: 2021-10-05T11:51:48-04:00
New Revision: 8f55fdf26cd9f08b3b706e9ff8819b0c7f72b651

URL: https://github.com/llvm/llvm-project/commit/8f55fdf26cd9f08b3b706e9ff8819b0c7f72b651
DIFF: https://github.com/llvm/llvm-project/commit/8f55fdf26cd9f08b3b706e9ff8819b0c7f72b651.diff

LOG: [MacroFusion] Expose useful static methods. NFC.

hasLessThanNumFused and fuseInstructionPair are useful for
DAG mutations similar to MacroFusion, but which cannot use
MacroFusion as a whole (such as fusing non-dependent instruction).

Reviewed By: MatzeB

Differential Revision: https://reviews.llvm.org/D111070

Change-Id: I3a5d56aba0471d45ef64cebb9b724030e2eae2f3

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/MacroFusion.h
    llvm/lib/CodeGen/MacroFusion.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/CodeGen/MacroFusion.h b/llvm/include/llvm/CodeGen/MacroFusion.h
index 3a140fe63fde..ea2c7a5faae3 100644
--- a/llvm/include/llvm/CodeGen/MacroFusion.h
+++ b/llvm/include/llvm/CodeGen/MacroFusion.h
@@ -23,6 +23,8 @@ class MachineInstr;
 class ScheduleDAGMutation;
 class TargetInstrInfo;
 class TargetSubtargetInfo;
+class ScheduleDAGInstrs;
+class SUnit;
 
 /// Check if the instr pair, FirstMI and SecondMI, should be fused
 /// together. Given SecondMI, when FirstMI is unspecified, then check if
@@ -32,6 +34,18 @@ using ShouldSchedulePredTy = std::function<bool(const TargetInstrInfo &TII,
                                                 const MachineInstr *FirstMI,
                                                 const MachineInstr &SecondMI)>;
 
+/// Checks if the number of cluster edges between SU and its predecessors is
+/// less than FuseLimit
+bool hasLessThanNumFused(const SUnit &SU, unsigned FuseLimit);
+
+/// Create an artificial edge between FirstSU and SecondSU.
+/// Make data dependencies from the FirstSU also dependent on the SecondSU to
+/// prevent them from being scheduled between the FirstSU and the SecondSU
+/// and vice-versa.
+/// Fusing more than 2 instructions is not currently supported.
+bool fuseInstructionPair(ScheduleDAGInstrs &DAG, SUnit &FirstSU,
+                         SUnit &SecondSU);
+
 /// Create a DAG scheduling mutation to pair instructions back to back
 /// for instructions that benefit according to the target-specific
 /// shouldScheduleAdjacent predicate function.

diff  --git a/llvm/lib/CodeGen/MacroFusion.cpp b/llvm/lib/CodeGen/MacroFusion.cpp
index d2ee21c8720f..b0760322064c 100644
--- a/llvm/lib/CodeGen/MacroFusion.cpp
+++ b/llvm/lib/CodeGen/MacroFusion.cpp
@@ -44,15 +44,15 @@ static SUnit *getPredClusterSU(const SUnit &SU) {
   return nullptr;
 }
 
-static bool hasLessThanNumFused(const SUnit &SU, unsigned FuseLimit) {
+bool llvm::hasLessThanNumFused(const SUnit &SU, unsigned FuseLimit) {
   unsigned Num = 1;
   const SUnit *CurrentSU = &SU;
   while ((CurrentSU = getPredClusterSU(*CurrentSU)) && Num < FuseLimit) Num ++;
   return Num < FuseLimit;
 }
 
-static bool fuseInstructionPair(ScheduleDAGInstrs &DAG, SUnit &FirstSU,
-                                SUnit &SecondSU) {
+bool llvm::fuseInstructionPair(ScheduleDAGInstrs &DAG, SUnit &FirstSU,
+                               SUnit &SecondSU) {
   // Check that neither instr is already paired with another along the edge
   // between them.
   for (SDep &SI : FirstSU.Succs)