[llvm][CodeGen] Added a new restriction for II by pragma in window scheduler #99448

kaiyan96 · 2024-07-18T08:24:47Z

Added a new restriction for window scheduling.
Window scheduling is disabled when llvm.loop.pipeline.initiationinterval is set.

…heduler

llvmbot · 2024-07-18T08:25:19Z

@llvm/pr-subscribers-backend-hexagon

Author: Kai Yan (kaiyan96)

Changes

Added a new restriction for II by pragma.
The window scheduler will not support loops if the Swing Scheduler's II pragma is set.

Full diff: https://github.com/llvm/llvm-project/pull/99448.diff

2 Files Affected:

(modified) llvm/lib/CodeGen/MachinePipeliner.cpp (+6-2)
(added) llvm/test/CodeGen/Hexagon/swp-ws-pragma-initiation-interval-fail.mir (+85)

diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index 497e282bb9768..f97f55d2d3faa 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -528,8 +528,12 @@ bool MachinePipeliner::useSwingModuloScheduler() {
 }
 
 bool MachinePipeliner::useWindowScheduler(bool Changed) {
-  // WindowScheduler does not work when it is off or when SwingModuloScheduler
-  // is successfully scheduled.
+  // WindowScheduler does not work for following cases:
+  // 1. when it is off.
+  // 2. when SwingModuloScheduler is successfully scheduled.
+  // 3. when pragma II is enabled.
+  if (II_setByPragma)
+    return false;
   return WindowSchedulingOption == WindowSchedulingFlag::WS_Force ||
          (WindowSchedulingOption == WindowSchedulingFlag::WS_On && !Changed);
 }
diff --git a/llvm/test/CodeGen/Hexagon/swp-ws-pragma-initiation-interval-fail.mir b/llvm/test/CodeGen/Hexagon/swp-ws-pragma-initiation-interval-fail.mir
new file mode 100644
index 0000000000000..81dc60086ecca
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/swp-ws-pragma-initiation-interval-fail.mir
@@ -0,0 +1,85 @@
+# RUN: llc  --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
+# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
+# RUN: | FileCheck %s
+# REQUIRES: asserts
+
+# Test that checks no window scheduler is performed if the II set by pragma was
+# enabled
+
+# CHECK-NOT: Start analyzing II
+# CHECK-NOT: Start scheduling Phis
+# CHECK-NOT: Current window Offset is {{[0-9]+}} and II is {{[0-9]+}}
+
+--- |
+  define void @test_pragma_ii_fail(ptr %a0, i32 %a1) {
+  b0:
+    %v0 = icmp sgt i32 %a1, 1
+    br i1 %v0, label %b1, label %b4
+
+  b1:                                               ; preds = %b0
+    %v1 = load i32, ptr %a0, align 4
+    %v2 = add i32 %v1, 10
+    %v4 = add i32 %a1, -1
+    %cgep = getelementptr i32, ptr %a0, i32 1
+    br label %b2
+
+  b2:                                               ; preds = %b2, %b1
+    %v5 = phi i32 [ %v12, %b2 ], [ %v4, %b1 ]
+    %v6 = phi ptr [ %cgep2, %b2 ], [ %cgep, %b1 ]
+    %v7 = phi i32 [ %v10, %b2 ], [ %v2, %b1 ]
+    store i32 %v7, ptr %v6, align 4
+    %v8 = add i32 %v7, 10
+    %cgep1 = getelementptr i32, ptr %v6, i32 -1
+    store i32 %v8, ptr %cgep1, align 4
+    %v10 = add i32 %v7, 10
+    %v12 = add i32 %v5, -1
+    %v13 = icmp eq i32 %v12, 0
+    %cgep2 = getelementptr i32, ptr %v6, i32 1
+    br i1 %v13, label %b4, label %b2, !llvm.loop !0
+
+  b4:                                               ; preds = %b2, %b0
+    ret void
+  }
+
+  !0 = distinct !{!0, !1}
+  !1 = !{!"llvm.loop.pipeline.initiationinterval", i32 2}
+...
+---
+name:            test_pragma_ii_fail
+tracksRegLiveness: true
+body:             |
+  bb.0.b0:
+    successors: %bb.1(0x40000000), %bb.3(0x40000000)
+    liveins: $r0, $r1
+  
+    %0:intregs = COPY $r1
+    %1:intregs = COPY $r0
+    %2:predregs = C2_cmpgti %0, 1
+    J2_jumpf %2, %bb.3, implicit-def dead $pc
+    J2_jump %bb.1, implicit-def dead $pc
+  
+  bb.1.b1:
+    successors: %bb.2(0x80000000)
+  
+    %3:intregs, %4:intregs = L2_loadri_pi %1, 4
+    %5:intregs = A2_addi killed %3, 10
+    %6:intregs = A2_addi %0, -1
+    %7:intregs = COPY %6
+    J2_loop0r %bb.2, %7, implicit-def $lc0, implicit-def $sa0, implicit-def $usr
+  
+  bb.2.b2 (machine-block-address-taken):
+    successors: %bb.3(0x04000000), %bb.2(0x7c000000)
+  
+    %8:intregs = PHI %4, %bb.1, %9, %bb.2
+    %10:intregs = PHI %5, %bb.1, %11, %bb.2
+    S2_storeri_io %8, 0, %10
+    %11:intregs = A2_addi %10, 10
+    S2_storeri_io %8, -4, %11
+    %9:intregs = A2_addi %8, 4
+    ENDLOOP0 %bb.2, implicit-def $pc, implicit-def $lc0, implicit $sa0, implicit $lc0
+    J2_jump %bb.3, implicit-def dead $pc
+  
+  bb.3.b4:
+    PS_jmpret $r31, implicit-def dead $pc
+
+...

arsenm · 2024-07-19T10:15:38Z

llvm/test/CodeGen/Hexagon/swp-ws-pragma-initiation-interval-fail.mir

+# CHECK-NOT: Start analyzing II
+# CHECK-NOT: Start scheduling Phis
+# CHECK-NOT: Current window Offset is {{[0-9]+}} and II is {{[0-9]+}}


-NOT checks are too fragile, especially for unstable debug printing

We have added new debug information to report that the window scheduler is not supported when the initiation interval is set by pragma. Since window scheduling is not operated, this debug information is the only way to determine the status of the window scheduler.

…sed on review comments

arsenm · 2024-07-22T07:53:14Z

llvm/lib/CodeGen/MachinePipeliner.cpp

+  // 3. when pragma II is enabled.
+  if (II_setByPragma) {
+    LLVM_DEBUG(
+        dbgs() << "Window scheduling is disabled when Pragma II is set.\n");


Message doesn't sound like it means anything, probably should name as the metadata?

Is it better to change the debug message to:

if (II_setByPragma) { LLVM_DEBUG( dbgs() << "Window scheduling is disabled when llvm.loop.pipeline.initiationinterval is set.\n"); }

…sed on review comments llvm#2

…heduler (#99448) Summary: Added a new restriction for window scheduling. Window scheduling is disabled when llvm.loop.pipeline.initiationinterval is set. Test Plan: Reviewers: Subscribers: Tasks: Tags: Differential Revision: https://phabricator.intern.facebook.com/D60250697

…heduler (llvm#99448) Added a new restriction for window scheduling. Window scheduling is disabled when llvm.loop.pipeline.initiationinterval is set.

kaiyan96 · 2024-08-13T03:11:34Z

/cherry-pick 0c7e10d

llvmbot · 2024-08-13T03:16:19Z

/cherry-pick 0c7e10d

Error: Command failed due to missing milestone.

llvmbot · 2024-08-13T03:18:13Z

/cherry-pick 0c7e10d

Error: Command failed due to missing milestone.

llvmbot · 2024-08-13T03:21:02Z

/cherry-pick 0c7e10d

Error: Command failed due to missing milestone.

kaiyan96 · 2024-08-15T02:20:28Z

/cherry-pick cd1a2ed

llvmbot · 2024-08-15T02:25:30Z

Failed to cherry-pick: cd1a2ed

https://github.com/llvm/llvm-project/actions/runs/10397731122

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

…heduler (llvm#99448) Added a new restriction for window scheduling. Window scheduling is disabled when llvm.loop.pipeline.initiationinterval is set.

[llvm][CodeGen] Added a new restriction for II by pragma in window sc…

75a84b1

…heduler

llvmbot added the backend:Hexagon label Jul 18, 2024

huaatian requested a review from arsenm July 18, 2024 08:35

This was referenced Jul 18, 2024

[llvm][CodeGen] Fixed max cycle calculation with zero-cost instructions for window scheduler #99454

Merged

[llvm][CodeGen] Some bugfix for window scheduler #99429

Closed

huaatian added the mi-sched machine instruction scheduler label Jul 18, 2024

arsenm reviewed Jul 19, 2024

View reviewed changes

[llvm][CodeGen] Modifications made for II by pragma WS restriction ba…

e3f6ada

…sed on review comments

arsenm approved these changes Jul 22, 2024

View reviewed changes

[llvm][CodeGen] Modifications made for II by pragma WS restriction ba…

77ace75

…sed on review comments llvm#2

arsenm approved these changes Jul 22, 2024

View reviewed changes

huaatian merged commit cd1a2ed into llvm:main Jul 24, 2024
7 checks passed

kaiyan96 mentioned this pull request Aug 5, 2024

[llvm][CodeGen] Address the issue of multiple resource reservations In window scheduling #101665

Merged

kaiyan96 mentioned this pull request Aug 12, 2024

release/19.x: [llvm][CodeGen] Address the issue discovered In window scheduling (#101665) #102881

Merged

huaatian added this to the LLVM 19.X Release milestone Aug 13, 2024

llvmbot added the release:cherry-pick-failed label Aug 15, 2024

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[llvm][CodeGen] Added a new restriction for II by pragma in window scheduler #99448

[llvm][CodeGen] Added a new restriction for II by pragma in window scheduler #99448

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[llvm][CodeGen] Added a new restriction for II by pragma in window scheduler #99448

[llvm][CodeGen] Added a new restriction for II by pragma in window scheduler #99448

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