[llvm] ed47a9c - [Attributor][FIX] Handle the default case of a switch

[Johannes Doerfert via llvm-commits]

Author: Johannes Doerfert
Date: 2019-11-02T00:30:31-05:00
New Revision: ed47a9cde4f667058ac34ef7805fc4093a5a4f7b

URL: https://github.com/llvm/llvm-project/commit/ed47a9cde4f667058ac34ef7805fc4093a5a4f7b
DIFF: https://github.com/llvm/llvm-project/commit/ed47a9cde4f667058ac34ef7805fc4093a5a4f7b.diff

LOG: [Attributor][FIX] Handle the default case of a switch

In D69605 only the "cases" of a switch were handled but if none matched
we did not make the default case life. This is fixed now and properly
tested (with code from IPConstantProp/user-with-multiple-uses.ll).

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/Attributor.cpp
    llvm/test/Transforms/FunctionAttrs/liveness.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 9fdfed8dbedb..3d6a2c6f94f6 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -2576,23 +2576,23 @@ static bool
 identifyAliveSuccessors(Attributor &A, const SwitchInst &SI,
                         AbstractAttribute &AA,
                         SmallVectorImpl<const Instruction *> &AliveSuccessors) {
-  bool UsedAssumedInformation = false;
-    Optional<ConstantInt *> CI = getAssumedConstant(A, *SI.getCondition(), AA);
+  Optional<ConstantInt *> CI = getAssumedConstant(A, *SI.getCondition(), AA);
   if (!CI.hasValue()) {
     // No value yet, assume all edges are dead.
   } else if (CI.getValue()) {
     for (auto &CaseIt : SI.cases()) {
       if (CaseIt.getCaseValue() == CI.getValue()) {
         AliveSuccessors.push_back(&CaseIt.getCaseSuccessor()->front());
-        UsedAssumedInformation = true;
-        break;
+        return true;
       }
     }
+    AliveSuccessors.push_back(&SI.getDefaultDest()->front());
+    return true;
   } else {
     for (const BasicBlock *SuccBB : successors(SI.getParent()))
       AliveSuccessors.push_back(&SuccBB->front());
   }
-  return UsedAssumedInformation;
+  return false;
 }
 
 ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {

diff  --git a/llvm/test/Transforms/FunctionAttrs/liveness.ll b/llvm/test/Transforms/FunctionAttrs/liveness.ll
index 85afb10ca08f..2526d65bbf52 100644
--- a/llvm/test/Transforms/FunctionAttrs/liveness.ll
+++ b/llvm/test/Transforms/FunctionAttrs/liveness.ll
@@ -1,5 +1,6 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --scrub-attributes 
 ; RUN: opt -attributor --attributor-disable=false -attributor-max-iterations-verify -attributor-annotate-decl-cs -attributor-max-iterations=6 -S < %s | FileCheck %s
+; UTC_ARGS: --turn off
 
 declare void @no_return_call() nofree noreturn nounwind readnone
 
@@ -748,3 +749,43 @@ define void @useless_arg_ext_int_ext(i32* %a) {
   call void @useless_arg_ext_int(i32* %a)
   ret void
 }
+
+; UTC_ARGS: --turn on
+
+; FIXME: We should fold terminators.
+
+define internal i32 @switch_default(i64 %i) nounwind {
+; CHECK-LABEL: define {{[^@]+}}@switch_default
+; CHECK-SAME: (i64 [[I:%.*]])
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i64 0, label [[SW_DEFAULT:%.*]] [
+; CHECK-NEXT:    i64 3, label [[RETURN:%.*]]
+; CHECK-NEXT:    i64 10, label [[RETURN]]
+; CHECK-NEXT:    ]
+; CHECK:       sw.default:
+; CHECK-NEXT:    ret i32 123
+; CHECK:       return:
+; CHECK-NEXT:    unreachable
+;
+entry:
+  switch i64 %i, label %sw.default [
+  i64 3, label %return
+  i64 10, label %return
+  ]
+
+sw.default:
+  ret i32 123
+
+return:
+  ret i32 0
+}
+
+define i32 @switch_default_caller() {
+; CHECK-LABEL: define {{[^@]+}}@switch_default_caller()
+; CHECK-NEXT:    [[CALL2:%.*]] = tail call i32 @switch_default(i64 0)
+; CHECK-NEXT:    ret i32 123
+;
+  %call2 = tail call i32 @switch_default(i64 0)
+  ret i32 %call2
+}
+; UTC_ARGS: --turn off