[PATCH] D143457: [FuncSpec] Prevent assertion failure when no store value is found

[Jonathon Penix via Phabricator via llvm-commits]

jpenix-quic created this revision.
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If the only user of the Alloca argument provided to getPromotableAlloca()
is the same as the Call argument, StoreValue is never set and results
in an assertion failure that isa<> was used on a nullptr when passed into
getCandidateConstant().

This was originally seen when trying to build SPEC 2006 416.gamess using
flang with lto enabled.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D143457

Files:
  llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
  llvm/test/Transforms/FunctionSpecialization/compiler-crash-promote-alloca.ll


Index: llvm/test/Transforms/FunctionSpecialization/compiler-crash-promote-alloca.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/FunctionSpecialization/compiler-crash-promote-alloca.ll
@@ -0,0 +1,27 @@
+; RUN: opt -S --passes="ipsccp<func-spec>" -force-function-specialization < %s | FileCheck %s
+
+; Tests that `bar` has been specialized and that the compiler did not crash
+; while attempting to promote the alloca in `entry`.
+; CHECK: bar.1
+
+ at block = internal global [8 x i8] zeroinitializer, align 1
+
+define dso_local void @entry() {
+  %1 = alloca i32, align 4
+  call void @foo(ptr nonnull %1)
+  ret void
+}
+
+define internal void @foo(ptr nocapture readnone %0) {
+  %2 = alloca i32, align 4
+  call void @bar(ptr nonnull %2, ptr nonnull @block)
+  call void @bar(ptr nonnull %2, ptr nonnull getelementptr inbounds ([8 x i8], ptr @block, i64 0, i64 4))
+  ret void
+}
+
+define internal void @bar(ptr nocapture readonly %0, ptr nocapture readonly %1) {
+  %3 = load i32, ptr %0, align 4
+  %4 = load i32, ptr %1, align 4
+  ret void
+}
+
Index: llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
===================================================================
--- llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
+++ llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
@@ -125,6 +125,10 @@
     // Bail if there is any other unknown usage.
     return nullptr;
   }
+
+  if (!StoreValue)
+    return nullptr;
+
   return getCandidateConstant(StoreValue);
 }
 


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