Tweak bounds check elimination (#42692)

* Add GVN and move IRCE to allow more functions to vectorize
* Canonicalize arraysize(Vector, 1) to arraylen(Vector)

Co-authored-by: Prem Chintalapudi <premc@csail.mit.edu>
Co-authored-by: Valentin Churavy <vchuravy@users.noreply.github.com>

src/aotcompile.cpp

@@ -601,8 +601,6 @@ void addMachinePasses(legacy::PassManagerBase *PM, TargetMachine *TM, int optlev
         PM->add(createGVNPass());
 }
 
-
-
 // this defines the set of optimization passes defined for Julia at various optimization levels.
 // it assumes that the TLI and TTI wrapper passes have already been added.
 void addOptimizationPasses(legacy::PassManagerBase *PM, int opt_level,
@@ -729,7 +727,7 @@ void addOptimizationPasses(legacy::PassManagerBase *PM, int opt_level,
     PM->add(createLoopUnswitchPass());
     PM->add(createLICMPass());
     PM->add(createJuliaLICMPass());
-    PM->add(createInductiveRangeCheckEliminationPass());
+    PM->add(createInductiveRangeCheckEliminationPass()); // Must come before indvars
     // Subsequent passes not stripping metadata from terminator
     PM->add(createInstSimplifyLegacyPass());
     PM->add(createLoopIdiomPass());
@@ -749,13 +747,21 @@ void addOptimizationPasses(legacy::PassManagerBase *PM, int opt_level,
     PM->add(createMemCpyOptPass());
     PM->add(createSCCPPass());
 
+    //These next two passes must come before IRCE to eliminate the bounds check in #43308
+    PM->add(createCorrelatedValuePropagationPass());
+    PM->add(createDeadCodeEliminationPass());
+
+    PM->add(createInductiveRangeCheckEliminationPass()); // Must come between the two GVN passes
+
     // Run instcombine after redundancy elimination to exploit opportunities
     // opened up by them.
     // This needs to be InstCombine instead of InstSimplify to allow
     // loops over Union-typed arrays to vectorize.
     PM->add(createInstructionCombiningPass());
     PM->add(createJumpThreadingPass());
-    PM->add(createCorrelatedValuePropagationPass());
+    if (opt_level >= 3) {
+        PM->add(createGVNPass()); // Must come after JumpThreading and before LoopVectorize
+    }
     PM->add(createDeadStoreEliminationPass());
 
     // More dead allocation (store) deletion before loop optimization

src/cgutils.cpp

@@ -2401,13 +2401,22 @@ static intptr_t arraytype_maxsize(jl_value_t *ty)
     return INTPTR_MAX / elsz;
 }
 
+static Value *emit_arraylen(jl_codectx_t &ctx, const jl_cgval_t &tinfo);
+
 static Value *emit_arraysize(jl_codectx_t &ctx, const jl_cgval_t &tinfo, Value *dim)
 {
     size_t ndim;
     MDNode *tbaa = tbaa_arraysize;
     if (arraytype_constdim(tinfo.typ, &ndim)) {
         if (ndim == 0)
             return ConstantInt::get(T_size, 1);
+        if (ndim == 1) {
+            if (auto d = dyn_cast<ConstantInt>(dim)) {
+                if (d->getZExtValue() == 1) {
+                    return emit_arraylen(ctx, tinfo);
+                }
+            }
+        }
         if (ndim > 1) {
             if (tinfo.constant && isa<ConstantInt>(dim)) {
                 auto n = cast<ConstantInt>(dim)->getZExtValue() - 1;