[PATCH] D76378: [Attributor] Make use of analysis in the MustBeExecutedExplorer

[Shinji Okumura via Phabricator via llvm-commits]

okura created this revision.
okura added reviewers: jdoerfert, uenoku, sstefan1, baziotis.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

This commit was made to settle this issue on GitHub <https://github.com/llvm/llvm-project/issues/175>.
I added analysis getters for LoopInfo, DominatorTree, and PostDominatorTree. And I added a test to show an improvement of the deduction of `dereferenceable` attribute.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76378

Files:
  llvm/include/llvm/Transforms/IPO/Attributor.h
  llvm/test/Transforms/Attributor/dereferenceable-2.ll


Index: llvm/test/Transforms/Attributor/dereferenceable-2.ll
===================================================================
--- llvm/test/Transforms/Attributor/dereferenceable-2.ll
+++ llvm/test/Transforms/Attributor/dereferenceable-2.ll
@@ -354,3 +354,47 @@
   store double 0.000000e+00, double* %arg-cast
   ret void
 }
+
+; Make use of MustBeExecuted Explorer
+;
+; [CFG]
+; entry
+;  / \
+; l1 l2
+; | X |
+; l3 l4
+;  \ /
+;  l5
+;  / \
+; l6 l7
+;  \ /
+;  end
+; According to the above CFG, we can see that instructions in l5 Block must be executed.
+; Therefore, %p must be dereferenced.
+;
+; CHECK: define i32 @require_cfg_analysis(i32 %c, i32* dereferenceable(4) %p)
+define i32 @require_cfg_analysis(i32 %c, i32* %p) {
+  %tobool1 = icmp eq i32 %c, 0
+  br i1 %tobool1, label %l1, label %l2
+l1:                                       
+  %tobool2 = icmp eq i32 %c, 1
+  br i1 %tobool2, label %l3, label %l4
+l2:  
+  %tobool3 = icmp eq i32 %c, 2
+  br i1 %tobool3, label %l3, label %l4
+l3:
+  br label %l5
+l4:
+  br label %l5
+l5:
+  %tobool4 = icmp eq i32 %c, 4
+  br i1 %tobool4, label %l6, label %l7
+l6:
+  store i32 0, i32* %p
+  br label %end
+l7:
+  store i32 1, i32* %p
+  br label %end
+end:
+  ret i32 1
+}
Index: llvm/include/llvm/Transforms/IPO/Attributor.h
===================================================================
--- llvm/include/llvm/Transforms/IPO/Attributor.h
+++ llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -105,7 +105,9 @@
 #include "llvm/Analysis/CallGraph.h"
 #include "llvm/Analysis/InlineCost.h"
 #include "llvm/Analysis/LazyCallGraph.h"
+#include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/MustExecute.h"
+#include "llvm/Analysis/PostDominators.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/IR/CallSite.h"
@@ -560,7 +562,20 @@
                    SetVector<Function *> *CGSCC)
       : DL(M.getDataLayout()),
         Explorer(/* ExploreInterBlock */ true, /* ExploreCFGForward */ true,
-                 /* ExploreCFGBackward */ true),
+                 /* ExploreCFGBackward */ true,
+                 // LIGetter
+                 [](const Function &F) {
+                   return new LoopInfo(
+                       *(new DominatorTree(const_cast<Function &>(F))));
+                 },
+                 // DTGetter
+                 [](const Function &F) {
+                   return new DominatorTree(const_cast<Function &>(F));
+                 },
+                 // PDTGetter
+                 [](const Function &F) {
+                   return new PostDominatorTree(const_cast<Function &>(F));
+                 }),
         AG(AG), CGSCC(CGSCC) {}
 
   /// A map type from opcodes to instructions with this opcode.


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