[polly] [Polly][DebugInfo] Use getStableDebugLoc to avoid intrinsic-dependent behaviour (PR #81246)

[Stephen Tozer via llvm-commits]

https://github.com/SLTozer created https://github.com/llvm/llvm-project/pull/81246

Polly currently uses `getDebugLoc` in a few places to produce diagnostic output; this is correct when interacting with specific instructions, but may be incorrect when dealing with instruction ranges if debug intrinsics are included. As a general rule, the debug locations attached to debug intrinsics may be misleading compared to the surrounding instructions, and are not generally used for anything other than determining variable scope info; the recommended approach is therefore to use `getStableDebugLoc` instead, which skips over debug intrinsics. This is necessary to fix test failures that occur when enabling non-instruction debug info, which removes debug intrinsics from basic blocks and thus alters the diagnostic output of Polly (despite causing no functional change).

>From 8fdaa53a1f61ed379ba5128a8b4510d0cc39ff67 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <Stephen.Tozer at Sony.com>
Date: Thu, 8 Feb 2024 19:03:48 +0000
Subject: [PATCH] Use getStableDebugLoc in Polly to avoid intrinsic-dependent
 behaviour

---
 polly/lib/Analysis/ScopDetectionDiagnostic.cpp            | 4 ++--
 polly/lib/Support/ScopLocation.cpp                        | 2 +-
 polly/test/ScopDetectionDiagnostics/ReportLoopBound-01.ll | 8 ++++----
 .../ScopDetectionDiagnostics/loop_has_multiple_exits.ll   | 2 +-
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/polly/lib/Analysis/ScopDetectionDiagnostic.cpp b/polly/lib/Analysis/ScopDetectionDiagnostic.cpp
index 364e21aef207ce..30fbd17c78bfe7 100644
--- a/polly/lib/Analysis/ScopDetectionDiagnostic.cpp
+++ b/polly/lib/Analysis/ScopDetectionDiagnostic.cpp
@@ -122,7 +122,7 @@ void getDebugLocations(const BBPair &P, DebugLoc &Begin, DebugLoc &End) {
       continue;
     Todo.append(succ_begin(BB), succ_end(BB));
     for (const Instruction &Inst : *BB) {
-      DebugLoc DL = Inst.getDebugLoc();
+      DebugLoc DL = Inst.getStableDebugLoc();
       if (!DL)
         continue;
 
@@ -821,7 +821,7 @@ std::string ReportUnprofitable::getEndUserMessage() const {
 const DebugLoc &ReportUnprofitable::getDebugLoc() const {
   for (const BasicBlock *BB : R->blocks())
     for (const Instruction &Inst : *BB)
-      if (const DebugLoc &DL = Inst.getDebugLoc())
+      if (const DebugLoc &DL = Inst.getStableDebugLoc())
         return DL;
 
   return R->getEntry()->getTerminator()->getDebugLoc();
diff --git a/polly/lib/Support/ScopLocation.cpp b/polly/lib/Support/ScopLocation.cpp
index 01f3d68926d88d..9f9941d57ad26a 100644
--- a/polly/lib/Support/ScopLocation.cpp
+++ b/polly/lib/Support/ScopLocation.cpp
@@ -25,7 +25,7 @@ void getDebugLocation(const Region *R, unsigned &LineBegin, unsigned &LineEnd,
 
   for (const BasicBlock *BB : R->blocks())
     for (const Instruction &Inst : *BB) {
-      DebugLoc DL = Inst.getDebugLoc();
+      DebugLoc DL = Inst.getStableDebugLoc();
       if (!DL)
         continue;
 
diff --git a/polly/test/ScopDetectionDiagnostics/ReportLoopBound-01.ll b/polly/test/ScopDetectionDiagnostics/ReportLoopBound-01.ll
index 618237157e084f..35986b5e0b3525 100644
--- a/polly/test/ScopDetectionDiagnostics/ReportLoopBound-01.ll
+++ b/polly/test/ScopDetectionDiagnostics/ReportLoopBound-01.ll
@@ -19,20 +19,20 @@
 
 ; If we reject non-affine loops the non-affine loop bound will be reported:
 ;
-; REJECTNONAFFINELOOPS: remark: ReportLoopBound-01.c:1:12: The following errors keep this region from being a Scop.
+; REJECTNONAFFINELOOPS: remark: ReportLoopBound-01.c:2:8: The following errors keep this region from being a Scop.
 ; REJECTNONAFFINELOOPS: remark: ReportLoopBound-01.c:2:8: Failed to derive an affine function from the loop bounds.
 ; REJECTNONAFFINELOOPS: remark: ReportLoopBound-01.c:3:5: Invalid Scop candidate ends here.
 
 ; If we allow non-affine loops the non-affine access will be reported:
 ;
-; ALLOWNONAFFINELOOPS: remark: ReportLoopBound-01.c:1:12: The following errors keep this region from being a Scop.
+; ALLOWNONAFFINELOOPS: remark: ReportLoopBound-01.c:2:8: The following errors keep this region from being a Scop.
 ; ALLOWNONAFFINELOOPS: remark: ReportLoopBound-01.c:3:5: The array subscript of "A" is not affine
 ; ALLOWNONAFFINELOOPS: remark: ReportLoopBound-01.c:3:5: Invalid Scop candidate ends here.
 
 ; If we allow non-affine loops and non-affine accesses the region will be reported as not profitable:
 ;
-; ALLOWNONAFFINEALL: remark: ReportLoopBound-01.c:1:12: The following errors keep this region from being a Scop.
-; ALLOWNONAFFINEALL: remark: ReportLoopBound-01.c:1:12: No profitable polyhedral optimization found
+; ALLOWNONAFFINEALL: remark: ReportLoopBound-01.c:2:8: The following errors keep this region from being a Scop.
+; ALLOWNONAFFINEALL: remark: ReportLoopBound-01.c:2:8: No profitable polyhedral optimization found
 ; ALLOWNONAFFINEALL: remark: ReportLoopBound-01.c:3:5: Invalid Scop candidate ends here.
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/polly/test/ScopDetectionDiagnostics/loop_has_multiple_exits.ll b/polly/test/ScopDetectionDiagnostics/loop_has_multiple_exits.ll
index 7661bd004f5c04..a0f2704b137232 100644
--- a/polly/test/ScopDetectionDiagnostics/loop_has_multiple_exits.ll
+++ b/polly/test/ScopDetectionDiagnostics/loop_has_multiple_exits.ll
@@ -2,7 +2,7 @@
 ;
 ; Derived from test-suite/MultiSource/Benchmarks/BitBench/uuencode/uuencode.c
 ;
-; CHECK: remark: uuencode.c:75:18: The following errors keep this region from being a Scop.
+; CHECK: remark: uuencode.c:76:13: The following errors keep this region from being a Scop.
 ; CHECK: remark: uuencode.c:83:3: Loop cannot be handled because it has multiple exits.
 ; CHECK: remark: uuencode.c:95:21: Invalid Scop candidate ends here.