PNaCl: Handle nested structure types in -expand-struct-regs.

test/Transforms/NaCl/expand-struct-regs.ll

 ; RUN: opt %s -expand-struct-regs -S | FileCheck %s
 ; RUN: opt %s -expand-struct-regs -S | FileCheck %s -check-prefix=CLEANUP
 
 ; These two instructions should not appear in the output:
 ; CLEANUP-NOT: extractvalue
 ; CLEANUP-NOT: insertvalue
 
 %struct = type { i8, i32 }
 
 
@@ skipping 106 matching lines @@
 ; CHECK-NEXT: store i32 200, i32* %out1
 ; CHECK-NEXT: ret void
 
 
 define i32 @extract_from_constant() {
   %ev = extractvalue %struct { i8 99, i32 888 }, 1
   ret i32 %ev
 }
 ; CHECK: define i32 @extract_from_constant() {
 ; CHECK-NEXT: ret i32 888
+
+define void @nested_structs() {
+  %a1 = alloca i64
+  %a2 = alloca i32
+  %a3 = alloca { { i32, i64 } }
+  %a = insertvalue { i32, i64 } undef, i32 5, 0
+  %b = insertvalue { i32, i64 } %a, i64 6, 1
+  %c = insertvalue { { i32, i64 } } undef, { i32, i64 } %b, 0
+  %d = insertvalue { { { i32, i64 } }, i64 } undef, { { i32, i64 } } %c, 0
+  %e = insertvalue { { { i32, i64 } }, i64 } undef, { i32, i64 } %b, 0, 0
+
+  %f = extractvalue { { { i32, i64 } }, i64 } %d, 0, 0, 1
+  %g = extractvalue { { { i32, i64 } }, i64 } %e, 0, 0, 0
+  %h = extractvalue { { { i32, i64 } }, i64 } %e, 0
+  store i64 %f, i64* %a1
+  store i32 %g, i32* %a2
+  store { { i32, i64 } } %h, { { i32, i64 } }* %a3
+  ret void
+}
+; CHECK-LABEL: define void @nested_structs()
+; CHECK-NEXT:    %a1 = alloca i64
+; CHECK-NEXT:    %a2 = alloca i32
+; CHECK-NEXT:    %a3 = alloca { { i32, i64 } }
+; CHECK-NEXT:    store i64 6, i64* %a1
+; CHECK-NEXT:    store i32 5, i32* %a2
+; CHECK-NEXT:    %a3.index = getelementptr { { i32, i64 } }* %a3, i32 0, i32 0
+; CHECK-NEXT:    %a3.index.index = getelementptr { i32, i64 }* %a3.index, i32 0, i32 0
+; CHECK-NEXT:    store i32 5, i32* %a3.index.index, align 1
+; CHECK-NEXT:    %a3.index.index1 = getelementptr { i32, i64 }* %a3.index, i32 0, i32 1
+; CHECK-NEXT:    store i64 6, i64* %a3.index.index1, align 1
+
+define void @nested_structs_phi_load() {

[Mark Seaborn, 2014/12/09 20:39:46]

I'm not sure what this test case is intended to test.  It doesn't use nested
structs except for alloca & getelementptr, which I think work without this
changeset applied (since the pass doesn't change alloca/getelementptr).

Is this perhaps testing a corner case you found during development?  If so, that
would be worth commenting.

[Richard Diamond, 2014/12/10 00:58:06]

It's not. JF asked for a test with phi and load instructions, and thus 
@nested_structs_phi_load was born. Removed.

+entry:
+  %a3 = alloca { { i32, i64 }* }
+  %a = insertvalue { i32, i64 } undef, i32 5, 0
+  %b = insertvalue { i32, i64 } %a, i64 6, 1
+  %a4 = getelementptr { { i32, i64 }* }* %a3, i32 0, i32 0
+  br label %next
+
+next:
+  %n1 = phi { i32, i64 } [ %b, %entry ]
+  %n2 = phi { i32, i64 }** [ %a4, %entry ]
+  %n3 = load { i32, i64 }** %n2
+  store { i32, i64 } %n1, { i32, i64 }* %n3
+  %n4 = load { i32, i64 }* %n3
+  %n5 = extractvalue { i32, i64 } %n4, 0
+  %n6 = extractvalue { i32, i64 } %n4, 1
+  ret void
+}
+; CHECK-LABEL: define void @nested_structs_phi_load()
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    %a3 = alloca { { i32, i64 }* }
+; CHECK-NEXT:    %a4 = getelementptr { { i32, i64 }* }* %a3, i32 0, i32 0
+; CHECK-NEXT:    br label %next
+; CHECK:       next:
+; CHECK-NEXT:    %n1.index = phi i32 [ 5, %entry ]
+; CHECK-NEXT:    %n1.index1 = phi i64 [ 6, %entry ]
+; CHECK-NEXT:    %n2 = phi { i32, i64 }** [ %a4, %entry ]
+; CHECK-NEXT:    %n3 = load { i32, i64 }** %n2
+; CHECK-NEXT:    %n3.index = getelementptr { i32, i64 }* %n3, i32 0, i32 0
+; CHECK-NEXT:    store i32 %n1.index, i32* %n3.index, align 1
+; CHECK-NEXT:    %n3.index4 = getelementptr { i32, i64 }* %n3, i32 0, i32 1
+; CHECK-NEXT:    store i64 %n1.index1, i64* %n3.index4, align 1
+; CHECK-NEXT:    %n4.index = getelementptr { i32, i64 }* %n3, i32 0, i32 0
+; CHECK-NEXT:    %n4.field = load i32* %n4.index, align 1
+; CHECK-NEXT:    %n4.index5 = getelementptr { i32, i64 }* %n3, i32 0, i32 1
+; CHECK-NEXT:    %n4.field6 = load i64* %n4.index5, align 1
+; CHECK-NEXT:    ret void