[llvm] [RISCV] Add load/store clustering in post machine schedule (PR #111504)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: None (BoyaoWang430)

<details>
<summary>Changes</summary>

#<!-- -->73789 added load clustering and #<!-- -->73796 tried to add store clustering.
If post machine schedule is used, previous cluster of load/store which formed in machine schedule may break. In order to solve this, add load/sotre clustering to post machine schedule.

---
Full diff: https://github.com/llvm/llvm-project/pull/111504.diff


2 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVTargetMachine.cpp (+13) 
- (added) llvm/test/CodeGen/RISCV/misched-mem-clustering.mir (+64) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 089dc6c529193d..4c8faed5a4787a 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -363,6 +363,19 @@ class RISCVPassConfig : public TargetPassConfig {
     return DAG;
   }
 
+  ScheduleDAGInstrs *
+  createPostMachineScheduler(MachineSchedContext *C) const override {
+    ScheduleDAGMI *DAG = nullptr;
+    if (EnableMISchedLoadStoreClustering) {
+      DAG = createGenericSchedPostRA(C);
+      DAG->addMutation(createLoadClusterDAGMutation(
+          DAG->TII, DAG->TRI, /*ReorderWhileClustering=*/true));
+      DAG->addMutation(createStoreClusterDAGMutation(
+          DAG->TII, DAG->TRI, /*ReorderWhileClustering=*/true));
+    }
+    return DAG;
+  }
+  
   void addIRPasses() override;
   bool addPreISel() override;
   void addCodeGenPrepare() override;
diff --git a/llvm/test/CodeGen/RISCV/misched-mem-clustering.mir b/llvm/test/CodeGen/RISCV/misched-mem-clustering.mir
new file mode 100644
index 00000000000000..4764e08969da5d
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/misched-mem-clustering.mir
@@ -0,0 +1,64 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=riscv64 -x mir -mcpu=sifive-p470 -mattr=+use-postra-scheduler -verify-misched -enable-post-misched=true \
+# RUN:     -riscv-misched-load-store-clustering=false -debug-only=machine-scheduler \
+# RUN:     -start-before=machine-scheduler -stop-after=postmisched -o - 2>&1 < %s \
+# RUN:   | FileCheck -check-prefix=NOCLUSTER %s
+# RUN: llc -mtriple=riscv64 -x mir -mcpu=sifive-p470 -mattr=+use-postra-scheduler -verify-misched -enable-post-misched=true \
+# RUN:     -debug-only=machine-scheduler \
+# RUN:     -start-before=machine-scheduler -stop-after=postmisched -o - 2>&1 < %s \
+# RUN:   | FileCheck -check-prefix=MEMCLUSTER %s
+
+...
+---
+name:            mem_clustering_1
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x6, $x10, $x14, $x15, $x16, $x17
+    ; NOCLUSTER-LABEL: name: mem_clustering_1
+    ; NOCLUSTER: liveins: $x6, $x10, $x14, $x15, $x16, $x17
+    ; NOCLUSTER-NEXT: {{  $}}
+    ; NOCLUSTER-NEXT: renamable $x5 = LW renamable $x15, 0 :: (load (s32))
+    ; NOCLUSTER-NEXT: SW renamable $x14, renamable $x15, 0 :: (store (s32))
+    ; NOCLUSTER-NEXT: renamable $x11 = ADDW killed renamable $x6, killed renamable $x5
+    ; NOCLUSTER-NEXT: renamable $x7 = LW renamable $x15, 8 :: (load (s32))
+    ; NOCLUSTER-NEXT: renamable $x28 = LW renamable $x15, 16 :: (load (s32))
+    ; NOCLUSTER-NEXT: renamable $x29 = LW renamable $x15, 24 :: (load (s32))
+    ; NOCLUSTER-NEXT: renamable $x13 = ADDW killed renamable $x7, killed renamable $x28
+    ; NOCLUSTER-NEXT: SW renamable $x14, renamable $x15, 8 :: (store (s32))
+    ; NOCLUSTER-NEXT: SW renamable $x14, renamable $x15, 16 :: (store (s32))
+    ; NOCLUSTER-NEXT: SW killed renamable $x14, killed renamable $x15, 24 :: (store (s32))
+    ; NOCLUSTER-NEXT: renamable $x11 = ADDW killed renamable $x11, killed renamable $x13
+    ; NOCLUSTER-NEXT: renamable $x6 = ADDW killed renamable $x11, killed renamable $x29
+    ; NOCLUSTER-NEXT: PseudoRET
+    ;
+    ; MEMCLUSTER-LABEL: name: mem_clustering_1
+    ; MEMCLUSTER: liveins: $x6, $x10, $x14, $x15, $x16, $x17
+    ; MEMCLUSTER-NEXT: {{  $}}
+    ; MEMCLUSTER-NEXT: renamable $x5 = LW renamable $x15, 0 :: (load (s32))
+    ; MEMCLUSTER-NEXT: renamable $x7 = LW renamable $x15, 8 :: (load (s32))
+    ; MEMCLUSTER-NEXT: renamable $x28 = LW renamable $x15, 16 :: (load (s32))
+    ; MEMCLUSTER-NEXT: renamable $x29 = LW renamable $x15, 24 :: (load (s32))
+    ; MEMCLUSTER-NEXT: SW renamable $x14, renamable $x15, 0 :: (store (s32))
+    ; MEMCLUSTER-NEXT: SW renamable $x14, renamable $x15, 8 :: (store (s32))
+    ; MEMCLUSTER-NEXT: SW renamable $x14, renamable $x15, 16 :: (store (s32))
+    ; MEMCLUSTER-NEXT: SW killed renamable $x14, killed renamable $x15, 24 :: (store (s32))
+    ; MEMCLUSTER-NEXT: renamable $x11 = ADDW killed renamable $x6, killed renamable $x5
+    ; MEMCLUSTER-NEXT: renamable $x13 = ADDW killed renamable $x7, killed renamable $x28
+    ; MEMCLUSTER-NEXT: renamable $x11 = ADDW killed renamable $x11, killed renamable $x13
+    ; MEMCLUSTER-NEXT: renamable $x6 = ADDW killed renamable $x11, killed renamable $x29
+    ; MEMCLUSTER-NEXT: PseudoRET
+    renamable $x5 = LW renamable $x15, 0 :: (load (s32))
+    renamable $x7 = LW renamable $x15, 8 :: (load (s32))
+    renamable $x28 = LW renamable $x15, 16 :: (load (s32))
+    renamable $x29 = LW renamable $x15, 24 :: (load (s32))
+    SW renamable $x14, renamable $x15, 0 :: (store (s32))
+    SW renamable $x14, renamable $x15, 8 :: (store (s32))
+    SW renamable $x14, renamable $x15, 16 :: (store (s32))
+    SW renamable $x14, renamable $x15, 24 :: (store (s32))
+    renamable $x11 = ADDW killed renamable $x6, killed renamable $x5
+    renamable $x13 = ADDW killed renamable $x7, killed renamable $x28
+    renamable $x11 = ADDW killed renamable $x11, killed renamable $x13
+    renamable $x6 = ADDW killed renamable $x11, killed renamable $x29
+    PseudoRET
+...

``````````

</details>


https://github.com/llvm/llvm-project/pull/111504