[llvm] [MachinePipeliner] Use AliasAnalysis properly when analyzing loop-carried dependencies (PR #136691)

[Ryotaro Kasuga via llvm-commits]

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@@ -0,0 +1,72 @@
+# RUN: llc -mtriple=hexagon -run-pass pipeliner -debug-only=pipeliner %s -o /dev/null 2>&1 | FileCheck %s
+# REQUIRES: asserts
+
+# Test that pipeliner correctly detects the loop-carried dependency between the
+# load and the store, which is indicated by `Ord` dependency from SU(2) to
+# SU(4). Note that there is no dependency within a single iteration.
+
+# CHECK:      SU(2):   %7:intregs = L2_loadri_io %5:intregs, 0 :: (load (s32) from %ir.ptr.load)
+# CHECK-NEXT:   # preds left
+# CHECK-NEXT:   # succs left
+# CHECK-NEXT:   # rdefs left
+# CHECK-NEXT:   Latency
+# CHECK-NEXT:   Depth
+# CHECK-NEXT:   Height
+# CHECK-NEXT:   Predecessors:
+# CHECK-NEXT:     SU(0): Data Latency=0 Reg=%5
+# CHECK-NEXT:   Successors:
+# CHECK-DAG:      SU(3): Data Latency=2 Reg=%7
+# CHECK-DAG:      SU(4): Ord  Latency=1 Barrier
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kasuga-fj wrote:

This is an example of a dependency that has been missed.

https://github.com/llvm/llvm-project/pull/136691