From 337c6781800456c4852817e9702264567af08d71 Mon Sep 17 00:00:00 2001
From: Lucas C Wilcox <lucas@swirlee.com>
Date: Wed, 24 Jul 2024 13:12:53 -0700
Subject: [PATCH] Make warn missed transformations pass optional (#54871)

This makes the `WarnMissedTransformationsPass` compiler pass optional
and off by default.

This is a backport of 1fc9fe1219d602bba82e14dc2ad999d072de236f.
---
 src/codegen-stubs.c |  2 +-
 src/jitlayers.h     |  6 ++++--
 src/pipeline.cpp    | 10 +++++++---
 test/misc.jl        | 20 ++++++++++++++++++++
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/src/codegen-stubs.c b/src/codegen-stubs.c
index b48ad7b98791fc..849dce666b1e21 100644
--- a/src/codegen-stubs.c
+++ b/src/codegen-stubs.c
@@ -110,7 +110,7 @@ JL_DLLEXPORT uint64_t jl_getUnwindInfo_fallback(uint64_t dwAddr)
 JL_DLLEXPORT void jl_add_optimization_passes_fallback(void *PM, int opt_level, int lower_intrinsics) UNAVAILABLE
 
 JL_DLLEXPORT void jl_build_newpm_pipeline_fallback(void *MPM, void *PB, int Speedup, int Size,
-    int lower_intrinsics, int dump_native, int external_use, int llvm_only) UNAVAILABLE
+    int lower_intrinsics, int dump_native, int external_use, int llvm_only, int warn_missed_transformations) UNAVAILABLE
 
 JL_DLLEXPORT void jl_register_passbuilder_callbacks_fallback(void *PB) { }
 
diff --git a/src/jitlayers.h b/src/jitlayers.h
index f57861fa567946..e6dae7a3b7ded5 100644
--- a/src/jitlayers.h
+++ b/src/jitlayers.h
@@ -90,13 +90,15 @@ struct OptimizationOptions {
     bool dump_native;
     bool external_use;
     bool llvm_only;
+    bool warn_missed_transformations;
 
     static constexpr OptimizationOptions defaults(
         bool lower_intrinsics=true,
         bool dump_native=false,
         bool external_use=false,
-        bool llvm_only=false) {
-        return {lower_intrinsics, dump_native, external_use, llvm_only};
+        bool llvm_only=false,
+        bool warn_missed_transformations=false) {
+        return {lower_intrinsics, dump_native, external_use, llvm_only, warn_missed_transformations};
     }
 };
 
diff --git a/src/pipeline.cpp b/src/pipeline.cpp
index 88c2da5d729c90..f4d394ca06df13 100644
--- a/src/pipeline.cpp
+++ b/src/pipeline.cpp
@@ -568,7 +568,9 @@ static void buildPipeline(ModulePassManager &MPM, PassBuilder *PB, OptimizationL
         if (O.getSpeedupLevel() >= 2) {
             buildVectorPipeline(FPM, PB, O, options);
         }
-        FPM.addPass(WarnMissedTransformationsPass());
+        if (options.warn_missed_transformations) {
+            FPM.addPass(WarnMissedTransformationsPass());
+        }
         MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
     }
     buildIntrinsicLoweringPipeline(MPM, PB, O, options);
@@ -577,7 +579,8 @@ static void buildPipeline(ModulePassManager &MPM, PassBuilder *PB, OptimizationL
 }
 
 extern "C" JL_DLLEXPORT_CODEGEN void jl_build_newpm_pipeline_impl(void *MPM, void *PB, int Speedup, int Size,
-    int lower_intrinsics, int dump_native, int external_use, int llvm_only) JL_NOTSAFEPOINT
+    int lower_intrinsics, int dump_native, int external_use, int llvm_only,
+    int warn_missed_transformations) JL_NOTSAFEPOINT
 {
     OptimizationLevel O;
     switch (Size) {
@@ -604,7 +607,7 @@ extern "C" JL_DLLEXPORT_CODEGEN void jl_build_newpm_pipeline_impl(void *MPM, voi
             }
     }
     buildPipeline(*reinterpret_cast<ModulePassManager*>(MPM), reinterpret_cast<PassBuilder*>(PB), O,
-                    OptimizationOptions{!!lower_intrinsics, !!dump_native, !!external_use, !!llvm_only});
+                    OptimizationOptions{!!lower_intrinsics, !!dump_native, !!external_use, !!llvm_only, !!warn_missed_transformations});
 }
 
 #undef JULIA_PASS
@@ -779,6 +782,7 @@ static llvm::Optional<std::pair<OptimizationLevel, OptimizationOptions>> parseJu
             OPTION(dump_native),
             OPTION(external_use),
             OPTION(llvm_only)
+            OPTION(warn_missed_transformations)
 #undef OPTION
         };
         while (!name.empty()) {
diff --git a/test/misc.jl b/test/misc.jl
index 79b684badf1e0e..64be037c5d9822 100644
--- a/test/misc.jl
+++ b/test/misc.jl
@@ -1402,3 +1402,23 @@ end
     GC.gc(true); yield()
     @test in_fin[]
 end
+
+@testset "Silenced missed transformations" begin
+    # Ensure the WarnMissedTransformationsPass is not on by default
+    src = """
+        @noinline iteration(i) = (@show(i); return nothing)
+        @eval function loop_unroll_full_fail(N)
+            for i in 1:N
+              iteration(i)
+              \$(Expr(:loopinfo, (Symbol("llvm.loop.unroll.full"), 1)))
+          end
+       end
+       loop_unroll_full_fail(3)
+    """
+    out_err = mktemp() do _, f
+        run(`$(Base.julia_cmd()) -e "$src"`, devnull, devnull, f)
+        seekstart(f)
+        read(f, String)
+    end
+    @test !occursin("loop not unrolled", out_err)
+end