Permit inactive register arguments on an indirect call (rust-lang#830)

Author: wsmoses

enzyme/Enzyme/AdjointGenerator.h

@@ -12062,16 +12062,18 @@ class AdjointGenerator
         Value *diffeadd = Builder2.CreateExtractValue(diffes, {structidx});
         ++structidx;
 
-        size_t size = 1;
-        if (orig->getArgOperand(i)->getType()->isSized())
-          size =
-              (gutils->newFunc->getParent()->getDataLayout().getTypeSizeInBits(
-                   orig->getArgOperand(i)->getType()) +
-               7) /
-              8;
+        if (!gutils->isConstantValue(orig->getArgOperand(i))) {
+          size_t size = 1;
+          if (orig->getArgOperand(i)->getType()->isSized())
+            size = (gutils->newFunc->getParent()
+                        ->getDataLayout()
+                        .getTypeSizeInBits(orig->getArgOperand(i)->getType()) +
+                    7) /
+                   8;
 
-        addToDiffe(orig->getArgOperand(i), diffeadd, Builder2,
-                   TR.addingType(size, orig->getArgOperand(i)));
+          addToDiffe(orig->getArgOperand(i), diffeadd, Builder2,
+                     TR.addingType(size, orig->getArgOperand(i)));
+        }
       }
     }
 

enzyme/test/Enzyme/ReverseMode/indirectcst.ll

@@ -0,0 +1,42 @@
+; RUN: %opt < %s %loadEnzyme -enzyme -enzyme-preopt=false -mem2reg -sroa -instsimplify -adce -correlated-propagation -simplifycfg -S | FileCheck %s
+
+declare dso_local double @__enzyme_autodiff(...)
+
+define double @square(double (double, double)* %add, double %x) {
+entry:
+  %mul = call double %add(double %x, double 1.0000000e+00)
+  ret double %mul
+}
+
+define double @dsquare(double (double, double)* %add, double (double, double)* %dadd, double %x) local_unnamed_addr {
+entry:
+  %call = tail call double (...) @__enzyme_autodiff(i8* bitcast (double (double (double, double)*, double)* @square to i8*), 
+    metadata !"enzyme_dup", double (double, double)* %add, double (double, double)* %dadd, double %x)
+  ret double %call
+}
+
+; CHECK: define internal { double } @diffesquare(double (double, double)* %add, double (double, double)* %"add'", double %x, double %differeturn)
+; CHECK-NEXT: entry:
+; CHECK-NEXT:   %0 = bitcast double (double, double)* %add to i8*
+; CHECK-NEXT:   %1 = bitcast double (double, double)* %"add'" to i8*
+; CHECK-NEXT:   %2 = icmp eq i8* %0, %1
+; CHECK-NEXT:   br i1 %2, label %error.i, label %__enzyme_runtimeinactiveerr.exit
+
+; CHECK: error.i:                                          ; preds = %entry
+; CHECK-NEXT:   %3 = call i32 @puts(i8* getelementptr inbounds ([79 x i8], [79 x i8]* @.str, i32 0, i32 0))
+; CHECK-NEXT:   call void @exit(i32 1)
+; CHECK-NEXT:   unreachable
+
+; CHECK: __enzyme_runtimeinactiveerr.exit:                 ; preds = %entry
+; CHECK-NEXT:   %4 = bitcast double (double, double)* %"add'" to { i8*, double } (double, double)**
+; CHECK-NEXT:   %5 = load { i8*, double } (double, double)*, { i8*, double } (double, double)** %4
+; CHECK-NEXT:   %mul_augmented = call { i8*, double } %5(double %x, double 1.000000e+00)
+; CHECK-NEXT:   %subcache = extractvalue { i8*, double } %mul_augmented, 0
+; CHECK-NEXT:   %6 = bitcast double (double, double)* %"add'" to { double, double } (double, double, double, i8*)**
+; CHECK-NEXT:   %7 = getelementptr { double, double } (double, double, double, i8*)*, { double, double } (double, double, double, i8*)** %6, i64 1
+; CHECK-NEXT:   %8 = load { double, double } (double, double, double, i8*)*, { double, double } (double, double, double, i8*)** %7
+; CHECK-NEXT:   %9 = call { double, double } %8(double %x, double 1.000000e+00, double %differeturn, i8* %subcache)
+; CHECK-NEXT:   %10 = extractvalue { double, double } %9, 0
+; CHECK-NEXT:   %11 = insertvalue { double } undef, double %10, 0
+; CHECK-NEXT:   ret { double } %11
+; CHECK-NEXT: }