StructurizeCFG: Fix inverting constantexpr conditions

[• tstellarAMD]

LGTM. Does this fix any real applications?

[arsenm]

In D22264#485918, @tstellarAMD wrote:

LGTM. Does this fix any real applications?

I think I hit this when reducing one of the mesa shaders I broke, but only after bugpoint inserted all of the undefs

[arsenm]

r275626

lib/Transforms/Scalar/StructurizeCFG.cpp

for (BasicBlock *Succ : Term->successors())
       if (Visited.count(Succ))
         Loops[Succ] = BB;
   }
 }
 
 /// \brief Invert the given condition
 Value *StructurizeCFG::invert(Value *Condition) {
   // First: Check if it's a constant
-  if (Condition == BoolTrue)
-    return BoolFalse;
-
-  if (Condition == BoolFalse)
-    return BoolTrue;
-
-  if (Condition == BoolUndef)
-    return BoolUndef;
+  if (Constant *C = dyn_cast<Constant>(Condition))
+    return ConstantExpr::getNot(C);
 
   // Second: If the condition is already inverted, return the original value
   if (match(Condition, m_Not(m_Value(Condition))))
     return Condition;
 
   if (Instruction *Inst = dyn_cast<Instruction>(Condition)) {
     // Third: Check all the users for an invert
     BasicBlock *Parent = Inst->getParent();

test/Transforms/StructurizeCFG/invert-constantexpr.ll

+; RUN: opt -S -o - -structurizecfg < %s | FileCheck %s
+
+; CHECK-LABEL: @invert_constantexpr_condition(
+; CHECK: %tmp5 = or i1 %tmp4, icmp eq (i32 bitcast (float fadd (float undef, float undef) to i32), i32 0)
+; CHECK: [ icmp ne (i32 bitcast (float fadd (float undef, float undef) to i32), i32 0), %bb ]
+define void @invert_constantexpr_condition(i32 %arg, i32 %arg1) #0 {
+bb:
+  %tmp = icmp eq i32 %arg, 0
+  br i1 icmp eq (i32 bitcast (float fadd (float undef, float undef) to i32), i32 0), label %bb2, label %bb6
+
+bb2:
+  br i1 %tmp, label %bb3, label %bb6
+
+bb3:
+  %tmp4 = phi i1 [ %tmp7, %bb6 ], [ undef, %bb2 ]
+  %tmp5 = or i1 %tmp4, icmp eq (i32 bitcast (float fadd (float undef, float undef) to i32), i32 0)
+  br i1 %tmp5, label %bb8, label %bb8
+
+bb6:
+  %tmp7 = icmp slt i32 %arg, %arg1
+  br label %bb3
+
+bb8:
+  ret void
+}
+
+declare i32 @llvm.amdgcn.workitem.id.x() #1
+
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone }