Compute the critical path length through a trace.
Whenever both instruction depths and instruction heights are known in a
block, it is possible to compute the length of the critical path as
max(depth+height) over the instructions in the block.
The stored live-in lists make it possible to accurately compute the
length of a critical path that bypasses the current (small) block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161197 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineTraceMetrics.h b/lib/CodeGen/MachineTraceMetrics.h
index b0edfeb..33c2d95 100644
--- a/lib/CodeGen/MachineTraceMetrics.h
+++ b/lib/CodeGen/MachineTraceMetrics.h
@@ -174,6 +174,11 @@
/// Instruction heights have been computed. This implies hasValidHeight().
bool HasValidInstrHeights;
+ /// Critical path length. This is the number of cycles in the longest data
+ /// dependency chain through the trace. This is only valid when both
+ /// HasValidInstrDepths and HasValidInstrHeights are set.
+ unsigned CriticalPath;
+
/// Live-in registers. These registers are defined above the current block
/// and used by this block or a block below it.
/// This does not include PHI uses in the current block, but it does
@@ -224,6 +229,7 @@
void computeTrace(const MachineBasicBlock*);
void computeDepthResources(const MachineBasicBlock*);
void computeHeightResources(const MachineBasicBlock*);
+ unsigned computeCrossBlockCriticalPath(const TraceBlockInfo&);
void computeInstrDepths(const MachineBasicBlock*);
void computeInstrHeights(const MachineBasicBlock*);
void addLiveIns(const MachineInstr *DefMI,