[PATCH] D109294: [Inline] Remove dead users before checking if function has one use (PR51667)

[Erik Desjardins via Phabricator via llvm-commits]

erikdesjardins updated this revision to Diff 371234.
erikdesjardins added a comment.
Herald added a subscriber: ormris.

move out of analysis; make test less fragile


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D109294/new/

https://reviews.llvm.org/D109294

Files:
  llvm/lib/Transforms/IPO/Inliner.cpp
  llvm/test/Transforms/Inline/inline-cost-dead-users.ll
  llvm/test/Transforms/Inline/last-callsite.ll


Index: llvm/test/Transforms/Inline/last-callsite.ll
===================================================================
--- llvm/test/Transforms/Inline/last-callsite.ll
+++ llvm/test/Transforms/Inline/last-callsite.ll
@@ -260,10 +260,10 @@
   ; constant expression cannot be inlined because the constant expression forms
   ; a second use. If this part starts failing we need to use more complex
   ; constant expressions to reference a particular function with them.
-  %sink = alloca i1
-  store volatile i1 icmp ne (i64 ptrtoint (void (i1)* @test4_g to i64), i64 ptrtoint(void (i1)* @test4_g to i64)), i1* %sink
+  %sink = alloca i64
+  store volatile i64 mul (i64 ptrtoint (void (i1)* @test4_g to i64), i64 ptrtoint(void (i1)* @test4_g to i64)), i64* %sink
   call void @test4_g(i1 true)
-; CHECK: store volatile i1 false
+; CHECK: store volatile i64 mul (i64 ptrtoint (void (i1)* @test4_g to i64), i64 ptrtoint (void (i1)* @test4_g to i64)), i64* %sink
 ; CHECK: call void @test4_g(i1 true)
 
   ret void
Index: llvm/test/Transforms/Inline/inline-cost-dead-users.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/Inline/inline-cost-dead-users.ll
@@ -0,0 +1,32 @@
+; Test to ensure that the inlining cost model isn't tripped up by dead constant users.
+; In this case, the call to g via a bitcasted function pointer is canonicalized to
+; a direct call to g with bitcasted arguments, leaving the original bitcast
+; as a dead use of g.
+
+; RUN: opt < %s -instcombine -inline -pass-remarks=inline -S 2>&1 \
+; RUN:     | FileCheck %s
+
+; Inline costs of f and g should be the same.
+
+; CHECK: 'f' inlined into 'h' with (cost=[[EXPECTED_COST:.+]], threshold={{.+}})
+; CHECK: 'g' inlined into 'h' with (cost=[[EXPECTED_COST]], threshold={{.+}})
+
+%0 = type { i64, i64, i64 }
+%1 = type { i64, i64, i64 }
+
+define internal void @f(%0* align 8 %a) unnamed_addr {
+start:
+  ret void
+}
+
+define internal void @g(%0* align 8 %a) unnamed_addr {
+start:
+  ret void
+}
+
+define void @h(%0* align 8 %a, %1* align 8 %b) unnamed_addr {
+start:
+  call void @f(%0* align 8 %a)
+  call void bitcast (void (%0*)* @g to void (%1*)*)(%1* align 8 %b)
+  ret void
+}
Index: llvm/lib/Transforms/IPO/Inliner.cpp
===================================================================
--- llvm/lib/Transforms/IPO/Inliner.cpp
+++ llvm/lib/Transforms/IPO/Inliner.cpp
@@ -826,6 +826,10 @@
         continue;
       }
 
+      // To make sure the inline cost is as accurate as possible,
+      // remove any dead users left by previous passes.
+      Callee.removeDeadConstantUsers();
+
       auto Advice = Advisor.getAdvice(*CB, OnlyMandatory);
       // Check whether we want to inline this callsite.
       if (!Advice->isInliningRecommended()) {


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