[LICM] Avoind store sinking if no preheader is available

Load instructions are inserted into loop preheaders when sinking stores
and later removed if not used by the SSA updater. Avoid sinking if the
loop has no preheader and avoid crashes. This fixes one more side effect
of not handling indirectbr instructions properly on LoopSimplify.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223119 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index c706248267ffa9d0647ec3aa3b3d9615c30763b2..99725b5f738c45d6d910796febb458887a280d85 100644 (file)
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -847,8 +847,10 @@ void LICM::PromoteAliasSet(AliasSet &AS,
           return;
         // Don't sink stores from loops without dedicated block exits. Exits
         // containing indirect branches are not transformed by loop simplify,
-        // make sure we catch that.
-        if (!HasDedicatedExits)
+        // make sure we catch that. An additional load may be generated in the
+        // preheader for SSA updater, so also avoid sinking when no preheader
+        // is available.
+        if (!HasDedicatedExits || !Preheader)
           return;
 
         // Note that we only check GuaranteedToExecute inside the store case

diff --git a/test/Transforms/LICM/sinking.ll b/test/Transforms/LICM/sinking.ll
index f01367b01aa51ce7d3c106dbf44b0dcbbd931eb6..d7a8fcdafcad185ca669aad34b560eb2b3fccafe 100644 (file)
--- a/test/Transforms/LICM/sinking.ll
+++ b/test/Transforms/LICM/sinking.ll
@@ -359,6 +359,39 @@ lab22:
   indirectbr i8* undef, [label %lab5, label %lab6, label %lab7]
 }
 
+; Test that we don't crash when trying to sink stores and there's no preheader
+; available (which is used for creating loads that may be used by the SSA
+; updater)
+define void @test13() {
+; CHECK-LABEL: @test13
+  br label %lab59
+
+lab19:
+  br i1 undef, label %lab20, label %lab38
+
+lab20:
+  br label %lab60
+
+lab21:
+  br i1 undef, label %lab22, label %lab38
+
+lab22:
+  br label %lab38
+
+lab38:
+  ret void
+
+lab59:
+  indirectbr i8* undef, [label %lab60, label %lab38]
+
+lab60:
+; CHECK: lab60:
+; CHECK: store
+; CHECK-NEXT: indirectbr
+  store i32 2145244101, i32* undef, align 4
+  indirectbr i8* undef, [label %lab21, label %lab19]
+}
+
 declare void @f(i32*)
 
 declare void @g()