[polly] [polly][ScheduleOptimizer] Use IslMaxOperationsGuard helper instead of explicit restoration (PR #79303)

[Karthika Devi C via llvm-commits]

https://github.com/kartcq updated https://github.com/llvm/llvm-project/pull/79303

>From 2b2445fb5d5a17b19ddaf0f8ec51c3fb0e98ff66 Mon Sep 17 00:00:00 2001
From: kartcq <quic_kartc at quicinc.com>
Date: Wed, 24 Jan 2024 06:06:35 -0800
Subject: [PATCH 1/2] [polly][ScheduleOptimizer] Use IslMaxOperationsGuard
 helper instead of explicit restoration

To fix long compile time issue of Schedule optimizer, patch #77280 sets
the upper cap on max ISL operations. In case of bailing out when isl
quota is hit, error handling behavior was restored manually. This
commit replaces the restoration code with IslMaxOperationsGuard helper
and also removes redundant early return.
---
 polly/lib/Transform/ScheduleOptimizer.cpp | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/polly/lib/Transform/ScheduleOptimizer.cpp b/polly/lib/Transform/ScheduleOptimizer.cpp
index 8ee2b66339adb..5a0ea3b406754 100644
--- a/polly/lib/Transform/ScheduleOptimizer.cpp
+++ b/polly/lib/Transform/ScheduleOptimizer.cpp
@@ -868,23 +868,14 @@ static void runIslScheduleOptimizer(
     SC = SC.set_validity(Validity);
     SC = SC.set_coincidence(Validity);
 
-    // Save error handling behavior
-    long MaxOperations = isl_ctx_get_max_operations(Ctx);
-    isl_ctx_set_max_operations(Ctx, ScheduleComputeOut);
-    Schedule = SC.compute_schedule();
-    bool ScheduleQuota = false;
-    if (isl_ctx_last_error(Ctx) == isl_error_quota) {
-      isl_ctx_reset_error(Ctx);
-      LLVM_DEBUG(
-          dbgs() << "Schedule optimizer calculation exceeds ISL quota\n");
-      ScheduleQuota = true;
-    }
-    isl_options_set_on_error(Ctx, ISL_ON_ERROR_ABORT);
-    isl_ctx_reset_operations(Ctx);
-    isl_ctx_set_max_operations(Ctx, MaxOperations);
+    {
+      IslMaxOperationsGuard MaxOpGuard(Ctx, ScheduleComputeOut);
+      Schedule = SC.compute_schedule();
 
-    if (ScheduleQuota)
-      return;
+      if (MaxOpGuard.hasQuotaExceeded())
+        LLVM_DEBUG(
+            dbgs() << "Schedule optimizer calculation exceeds ISL quota\n");
+    }
 
     isl_options_set_on_error(Ctx, OnErrorStatus);
 

>From c581e3af6fe391465e137a23bee33e928c816407 Mon Sep 17 00:00:00 2001
From: kartcq <quic_kartc at quicinc.com>
Date: Wed, 24 Jan 2024 06:06:35 -0800
Subject: [PATCH 2/2] [polly][ScheduleOptimizer] Use IslMaxOperationsGuard
 helper instead of explicit restoration

To fix long compile time issue of Schedule optimizer, patch #77280 sets
the upper cap on max ISL operations. In case of bailing out when isl
quota is hit, error handling behavior was restored manually. This
commit replaces the restoration code with IslMaxOperationsGuard helper
and also removes redundant early return. This way of using helper is
less error-prone as well.
---
 polly/lib/Transform/ScheduleOptimizer.cpp     | 23 ++++++-------------
 .../ScheduleOptimizer/schedule_computeout.ll  |  4 ++--
 2 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/polly/lib/Transform/ScheduleOptimizer.cpp b/polly/lib/Transform/ScheduleOptimizer.cpp
index 8ee2b66339adb..5a0ea3b406754 100644
--- a/polly/lib/Transform/ScheduleOptimizer.cpp
+++ b/polly/lib/Transform/ScheduleOptimizer.cpp
@@ -868,23 +868,14 @@ static void runIslScheduleOptimizer(
     SC = SC.set_validity(Validity);
     SC = SC.set_coincidence(Validity);
 
-    // Save error handling behavior
-    long MaxOperations = isl_ctx_get_max_operations(Ctx);
-    isl_ctx_set_max_operations(Ctx, ScheduleComputeOut);
-    Schedule = SC.compute_schedule();
-    bool ScheduleQuota = false;
-    if (isl_ctx_last_error(Ctx) == isl_error_quota) {
-      isl_ctx_reset_error(Ctx);
-      LLVM_DEBUG(
-          dbgs() << "Schedule optimizer calculation exceeds ISL quota\n");
-      ScheduleQuota = true;
-    }
-    isl_options_set_on_error(Ctx, ISL_ON_ERROR_ABORT);
-    isl_ctx_reset_operations(Ctx);
-    isl_ctx_set_max_operations(Ctx, MaxOperations);
+    {
+      IslMaxOperationsGuard MaxOpGuard(Ctx, ScheduleComputeOut);
+      Schedule = SC.compute_schedule();
 
-    if (ScheduleQuota)
-      return;
+      if (MaxOpGuard.hasQuotaExceeded())
+        LLVM_DEBUG(
+            dbgs() << "Schedule optimizer calculation exceeds ISL quota\n");
+    }
 
     isl_options_set_on_error(Ctx, OnErrorStatus);
 
diff --git a/polly/test/ScheduleOptimizer/schedule_computeout.ll b/polly/test/ScheduleOptimizer/schedule_computeout.ll
index eb59f0e36ac64..acc8601a31a83 100644
--- a/polly/test/ScheduleOptimizer/schedule_computeout.ll
+++ b/polly/test/ScheduleOptimizer/schedule_computeout.ll
@@ -1,8 +1,8 @@
-; RUN: opt %loadPolly -S -polly-optree -polly-delicm  -polly-opt-isl -polly-schedule-computeout=100000 -debug-only="polly-opt-isl" < %s 2>&1 | FileCheck %s
+; RUN: opt %loadPolly -S -polly-optree -polly-delicm  -polly-opt-isl -polly-schedule-computeout=10000 -debug-only="polly-opt-isl" < %s 2>&1 | FileCheck %s
 ; REQUIRES: asserts
 
 ; Bailout if the computations of schedule compute exceeds the max scheduling quota.
-; Max compute out is initialized to 300000, Here it is set to 100000 for test purpose.
+; Max compute out is initialized to 300000, Here it is set to 10000 for test purpose.
 
 target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
 target triple = "aarch64-unknown-linux-gnu"