[PATCH] D70737: [Attributor] Move pass after InstCombine to futher eliminate null pointer checks

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 created this revision.
xbolva00 added a reviewer: jdoerfert.
Herald added subscribers: llvm-commits, hiraditya, mehdi_amini.
Herald added a project: LLVM.

PR44149


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D70737

Files:
  llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
  llvm/test/Transforms/PhaseOrdering/null-check-elim.ll


Index: llvm/test/Transforms/PhaseOrdering/null-check-elim.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PhaseOrdering/null-check-elim.ll
@@ -0,0 +1,47 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -O3 -attributor-disable=false -S < %s                    | FileCheck %s --check-prefixes=ANY,OLDPM
+; RUN: opt -passes='default<O3>' -attributor-disable=false -S < %s  | FileCheck %s --check-prefixes=ANY,NEWPM
+
+ at p = external global [2 x i8*], align 16
+
+define void @test(i8* %arg, i32 %arg1) {
+; OLDPM-LABEL: @test(
+; OLDPM-NEXT:  bb5:
+; OLDPM-NEXT:    [[TMP:%.*]] = tail call i8* @strchr(i8* nofree nonnull dereferenceable(1) [[ARG:%.*]], i32 [[ARG1:%.*]]) #1
+; OLDPM-NEXT:    store i8* [[TMP]], i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @p, i64 0, i64 0), align 16
+; OLDPM-NEXT:    [[TMP4:%.*]] = tail call i8* @foo(i8* nonnull [[ARG]])
+; OLDPM-NEXT:    store i8* [[TMP4]], i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @p, i64 0, i64 1), align 8
+; OLDPM-NEXT:    ret void
+;
+; NEWPM-LABEL: @test(
+; NEWPM-NEXT:  bb:
+; NEWPM-NEXT:    [[TMP:%.*]] = tail call i8* @strchr(i8* nonnull dereferenceable(1) [[ARG:%.*]], i32 [[ARG1:%.*]])
+; NEWPM-NEXT:    store i8* [[TMP]], i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @p, i64 0, i64 0), align 16
+; NEWPM-NEXT:    [[TMP2:%.*]] = icmp eq i8* [[ARG]], null
+; NEWPM-NEXT:    br i1 [[TMP2]], label [[BB5:%.*]], label [[BB3:%.*]]
+; NEWPM:       bb3:
+; NEWPM-NEXT:    [[TMP4:%.*]] = tail call i8* @foo(i8* nonnull [[ARG]])
+; NEWPM-NEXT:    br label [[BB5]]
+; NEWPM:       bb5:
+; NEWPM-NEXT:    [[TMP6:%.*]] = phi i8* [ [[TMP4]], [[BB3]] ], [ null, [[BB:%.*]] ]
+; NEWPM-NEXT:    store i8* [[TMP6]], i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @p, i64 0, i64 1), align 8
+; NEWPM-NEXT:    ret void
+;
+bb:
+  %tmp = tail call i8* @strchr(i8* %arg, i32 %arg1)
+  store i8* %tmp, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @p, i64 0, i64 0), align 16
+  %tmp2 = icmp eq i8* %arg, null
+  br i1 %tmp2, label %bb5, label %bb3
+
+bb3:                                              ; preds = %bb
+  %tmp4 = tail call i8* @foo(i8* %arg)
+  br label %bb5
+
+bb5:                                              ; preds = %bb3, %bb
+  %tmp6 = phi i8* [ %tmp4, %bb3 ], [ null, %bb ]
+  store i8* %tmp6, i8** getelementptr inbounds ([2 x i8*], [2 x i8*]* @p, i64 0, i64 1), align 8
+  ret void
+}
+
+declare i8* @strchr(i8*, i32)
+declare i8* @foo(i8*)
Index: llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
===================================================================
--- llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -517,9 +517,6 @@
   MPM.add(createIPSCCPPass());          // IP SCCP
   MPM.add(createCalledValuePropagationPass());
 
-  // Infer attributes on declarations, call sites, arguments, etc.
-  MPM.add(createAttributorLegacyPass());
-
   MPM.add(createGlobalOptimizerPass()); // Optimize out global vars
   // Promote any localized global vars.
   MPM.add(createPromoteMemoryToRegisterPass());
@@ -527,6 +524,8 @@
   MPM.add(createDeadArgEliminationPass()); // Dead argument elimination
 
   addInstructionCombiningPass(MPM); // Clean up after IPCP & DAE
+  // Infer attributes on declarations, call sites, arguments, etc.
+  MPM.add(createAttributorLegacyPass());
   addExtensionsToPM(EP_Peephole, MPM);
   MPM.add(createCFGSimplificationPass()); // Clean up after IPCP & DAE
 


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