Generalize target-independent folding rules for sizeof to handle more

cases, and implement target-independent folding rules for alignof and
offsetof. Also, reassociate reassociative operators when it leads to
more folding.

Generalize ScalarEvolution's isOffsetOf to recognize offsetof on
arrays. Rename getAllocSizeExpr to getSizeOfExpr, and getFieldOffsetExpr
to getOffsetOfExpr, for consistency with analagous ConstantExpr routines.

Make the target-dependent folder promote GEP array indices to
pointer-sized integers, to make implicit casting explicit and exposed
to subsequent folding.

And add a bunch of testcases for this new functionality, and a bunch
of related existing functionality.

llvm-svn: 94987

1 files changed, 314 insertions, 35 deletions

diff --git a/llvm/test/Other/constant-fold-gep.ll b/llvm/test/Other/constant-fold-gep.ll
index 513918d58f6e..bb93dc761c4f 100644
--- a/llvm/test/Other/constant-fold-gep.ll
+++ b/llvm/test/Other/constant-fold-gep.ll
@@ -1,9 +1,32 @@
+; "PLAIN" - No optimizations. This tests the target-independent
+; constant folder.
 ; RUN: opt -S -o - < %s | FileCheck --check-prefix=PLAIN %s
+
+; "OPT" - Optimizations but no targetdata. This tests target-independent
+; folding in the optimizers.
 ; RUN: opt -S -o - -instcombine -globalopt < %s | FileCheck --check-prefix=OPT %s
 
+; "TO" - Optimizations and targetdata. This tests target-dependent
+; folding in the optimizers.
+; RUN: opt -S -o - -instcombine -globalopt -default-data-layout="e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64" < %s | FileCheck --check-prefix=TO %s
+
+; "SCEV" - ScalarEvolution but no targetdata.
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck --check-prefix=SCEV %s
+
+; ScalarEvolution with targetdata isn't interesting on these testcases
+; because ScalarEvolution doesn't attempt to duplicate all of instcombine's
+; and the constant folders' folding.
+
+; PLAIN: %0 = type { i1, double }
+; PLAIN: %1 = type { double, float, double, double }
+; PLAIN: %2 = type { i64, i64 }
+; OPT: %0 = type { i1, double }
+; OPT: %1 = type { double, float, double, double }
+; OPT: %2 = type { i64, i64 }
+
 ; The automatic constant folder in opt does not have targetdata access, so
 ; it can't fold gep arithmetic, in general. However, the constant folder run
-; from instcombine and global opt does, and can.
+; from instcombine and global opt can use targetdata.
 
 ; PLAIN: @G8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
 ; PLAIN: @G1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
@@ -11,74 +34,330 @@
 ; PLAIN: @F1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
 ; PLAIN: @H8 = global i8* getelementptr (i8* null, i32 -1)
 ; PLAIN: @H1 = global i1* getelementptr (i1* null, i32 -1)
+; OPT: @G8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
+; OPT: @G1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
+; OPT: @F8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
+; OPT: @F1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
+; OPT: @H8 = global i8* getelementptr (i8* null, i32 -1)
+; OPT: @H1 = global i1* getelementptr (i1* null, i32 -1)
+; TO: @G8 = global i8* null
+; TO: @G1 = global i1* null
+; TO: @F8 = global i8* inttoptr (i64 -1 to i8*)
+; TO: @F1 = global i1* inttoptr (i64 -1 to i1*)
+; TO: @H8 = global i8* inttoptr (i64 -1 to i8*)
+; TO: @H1 = global i1* inttoptr (i64 -1 to i1*)
+
+@G8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
+@G1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
+@F8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
+@F1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
+@H8 = global i8* getelementptr (i8* inttoptr (i32 0 to i8*), i32 -1)
+@H1 = global i1* getelementptr (i1* inttoptr (i32 0 to i1*), i32 -1)
+
+; The target-independent folder should be able to do some clever
+; simplifications on sizeof, alignof, and offsetof expressions. The
+; target-dependent folder should fold these down to constants.
+
+; PLAIN: @a = constant i64 mul (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2310)
+; PLAIN: @b = constant i64 ptrtoint (double* getelementptr (%0* null, i64 0, i32 1) to i64)
+; PLAIN: @c = constant i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2)
+; PLAIN: @d = constant i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 11)
+; PLAIN: @e = constant i64 ptrtoint (double* getelementptr (%1* null, i64 0, i32 2) to i64)
+; PLAIN: @f = constant i64 1
+; OPT: @a = constant i64 mul (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2310)
+; OPT: @b = constant i64 ptrtoint (double* getelementptr (%0* null, i64 0, i32 1) to i64)
+; OPT: @c = constant i64 mul (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2)
+; OPT: @d = constant i64 mul (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 11)
+; OPT: @e = constant i64 ptrtoint (double* getelementptr (%1* null, i64 0, i32 2) to i64)
+; OPT: @f = constant i64 1
+; TO: @a = constant i64 18480
+; TO: @b = constant i64 8
+; TO: @c = constant i64 16
+; TO: @d = constant i64 88
+; TO: @e = constant i64 16
+; TO: @f = constant i64 1
+
+@a = constant i64 mul (i64 3, i64 mul (i64 ptrtoint ({[7 x double], [7 x double]}* getelementptr ({[7 x double], [7 x double]}* null, i64 11) to i64), i64 5))
+@b = constant i64 ptrtoint ([13 x double]* getelementptr ({i1, [13 x double]}* null, i64 0, i32 1) to i64)
+@c = constant i64 ptrtoint (double* getelementptr ({double, double, double, double}* null, i64 0, i32 2) to i64)
+@d = constant i64 ptrtoint (double* getelementptr ([13 x double]* null, i64 0, i32 11) to i64)
+@e = constant i64 ptrtoint (double* getelementptr ({double, float, double, double}* null, i64 0, i32 2) to i64)
+@f = constant i64 ptrtoint (<{ i16, i128 }>* getelementptr ({i1, <{ i16, i128 }>}* null, i64 0, i32 1) to i64)
+
+; The target-dependent folder should cast GEP indices to integer-sized pointers.
+
+; PLAIN: @M = constant i64* getelementptr (i64* null, i32 1)
+; PLAIN: @N = constant i64* getelementptr (%2* null, i32 0, i32 1)
+; PLAIN: @O = constant i64* getelementptr ([2 x i64]* null, i32 0, i32 1)
+; OPT: @M = constant i64* getelementptr (i64* null, i32 1)
+; OPT: @N = constant i64* getelementptr (%2* null, i32 0, i32 1)
+; OPT: @O = constant i64* getelementptr ([2 x i64]* null, i32 0, i32 1)
+; TO: @M = constant i64* inttoptr (i64 8 to i64*)
+; TO: @N = constant i64* inttoptr (i64 8 to i64*)
+; TO: @O = constant i64* inttoptr (i64 8 to i64*)
+
+@M = constant i64* getelementptr (i64 *null, i32 1)
+@N = constant i64* getelementptr ({ i64, i64 } *null, i32 0, i32 1)
+@O = constant i64* getelementptr ([2 x i64] *null, i32 0, i32 1)
+
+; Duplicate all of the above as function return values rather than
+; global initializers.
+
 ; PLAIN: define i8* @goo8() nounwind {
-; PLAIN:   ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
+; PLAIN:   %t = bitcast i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1) to i8*
+; PLAIN:   ret i8* %t
 ; PLAIN: }
 ; PLAIN: define i1* @goo1() nounwind {
-; PLAIN:   ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
+; PLAIN:   %t = bitcast i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1) to i1*
+; PLAIN:   ret i1* %t
 ; PLAIN: }
 ; PLAIN: define i8* @foo8() nounwind {
-; PLAIN:   ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
+; PLAIN:   %t = bitcast i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2) to i8*
+; PLAIN:   ret i8* %t
 ; PLAIN: }
 ; PLAIN: define i1* @foo1() nounwind {
-; PLAIN:   ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
+; PLAIN:   %t = bitcast i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2) to i1*
+; PLAIN:   ret i1* %t
 ; PLAIN: }
 ; PLAIN: define i8* @hoo8() nounwind {
-; PLAIN:   ret i8* getelementptr (i8* null, i32 -1)
+; PLAIN:   %t = bitcast i8* getelementptr (i8* null, i32 -1) to i8*
+; PLAIN:   ret i8* %t
 ; PLAIN: }
 ; PLAIN: define i1* @hoo1() nounwind {
-; PLAIN:   ret i1* getelementptr (i1* null, i32 -1)
+; PLAIN:   %t = bitcast i1* getelementptr (i1* null, i32 -1) to i1*
+; PLAIN:   ret i1* %t
 ; PLAIN: }
-
-; OPT: @G8 = global i8* null
-; OPT: @G1 = global i1* null
-; OPT: @F8 = global i8* inttoptr (i64 -1 to i8*)
-; OPT: @F1 = global i1* inttoptr (i64 -1 to i1*)
-; OPT: @H8 = global i8* inttoptr (i64 -1 to i8*)
-; OPT: @H1 = global i1* inttoptr (i64 -1 to i1*)
 ; OPT: define i8* @goo8() nounwind {
-; OPT:   ret i8* null
+; OPT:   ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
 ; OPT: }
 ; OPT: define i1* @goo1() nounwind {
-; OPT:   ret i1* null
+; OPT:   ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
 ; OPT: }
 ; OPT: define i8* @foo8() nounwind {
-; OPT:   ret i8* inttoptr (i64 -1 to i8*)
+; OPT:   ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
 ; OPT: }
 ; OPT: define i1* @foo1() nounwind {
-; OPT:   ret i1* inttoptr (i64 -1 to i1*)
+; OPT:   ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
 ; OPT: }
 ; OPT: define i8* @hoo8() nounwind {
-; OPT:   ret i8* inttoptr (i64 -1 to i8*)
+; OPT:   ret i8* getelementptr (i8* null, i32 -1)
 ; OPT: }
 ; OPT: define i1* @hoo1() nounwind {
-; OPT:   ret i1* inttoptr (i64 -1 to i1*)
+; OPT:   ret i1* getelementptr (i1* null, i32 -1)
 ; OPT: }
-
-target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64"
-
-@G8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
-@G1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
-@F8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
-@F1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
-@H8 = global i8* getelementptr (i8* inttoptr (i32 0 to i8*), i32 -1)
-@H1 = global i1* getelementptr (i1* inttoptr (i32 0 to i1*), i32 -1)
+; TO: define i8* @goo8() nounwind {
+; TO:   ret i8* null
+; TO: }
+; TO: define i1* @goo1() nounwind {
+; TO:   ret i1* null
+; TO: }
+; TO: define i8* @foo8() nounwind {
+; TO:   ret i8* inttoptr (i64 -1 to i8*)
+; TO: }
+; TO: define i1* @foo1() nounwind {
+; TO:   ret i1* inttoptr (i64 -1 to i1*)
+; TO: }
+; TO: define i8* @hoo8() nounwind {
+; TO:   ret i8* inttoptr (i64 -1 to i8*)
+; TO: }
+; TO: define i1* @hoo1() nounwind {
+; TO:   ret i1* inttoptr (i64 -1 to i1*)
+; TO: }
+; SCEV: Classifying expressions for: @goo8
+; SCEV:   %t = bitcast i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1) to i8*
+; SCEV:   -->  ((-1 * sizeof(i8)) + inttoptr (i32 1 to i8*))
+; SCEV: Classifying expressions for: @goo1
+; SCEV:   %t = bitcast i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1) to i1*
+; SCEV:   -->  ((-1 * sizeof(i1)) + inttoptr (i32 1 to i1*))
+; SCEV: Classifying expressions for: @foo8
+; SCEV:   %t = bitcast i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2) to i8*
+; SCEV:   -->  ((-2 * sizeof(i8)) + inttoptr (i32 1 to i8*))
+; SCEV: Classifying expressions for: @foo1
+; SCEV:   %t = bitcast i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2) to i1*
+; SCEV:   -->  ((-2 * sizeof(i1)) + inttoptr (i32 1 to i1*))
+; SCEV: Classifying expressions for: @hoo8
+; SCEV:   -->  (-1 * sizeof(i8))
+; SCEV: Classifying expressions for: @hoo1
+; SCEV:   -->  (-1 * sizeof(i1))
 
 define i8* @goo8() nounwind {
-  ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
+  %t = bitcast i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1) to i8*
+  ret i8* %t
 }
 define i1* @goo1() nounwind {
-  ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
+  %t = bitcast i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1) to i1*
+  ret i1* %t
 }
 define i8* @foo8() nounwind {
-  ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
+  %t = bitcast i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2) to i8*
+  ret i8* %t
 }
 define i1* @foo1() nounwind {
-  ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
+  %t = bitcast i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2) to i1*
+  ret i1* %t
 }
 define i8* @hoo8() nounwind {
-  ret i8* getelementptr (i8* inttoptr (i32 0 to i8*), i32 -1)
+  %t = bitcast i8* getelementptr (i8* inttoptr (i32 0 to i8*), i32 -1) to i8*
+  ret i8* %t
 }
 define i1* @hoo1() nounwind {
-  ret i1* getelementptr (i1* inttoptr (i32 0 to i1*), i32 -1)
+  %t = bitcast i1* getelementptr (i1* inttoptr (i32 0 to i1*), i32 -1) to i1*
+  ret i1* %t
+}
+
+; PLAIN: define i64 @fa() nounwind {
+; PLAIN:   %t = bitcast i64 mul (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2310) to i64
+; PLAIN:   ret i64 %t
+; PLAIN: }
+; PLAIN: define i64 @fb() nounwind {
+; PLAIN:   %t = bitcast i64 ptrtoint (double* getelementptr (%0* null, i64 0, i32 1) to i64) to i64
+; PLAIN:   ret i64 %t
+; PLAIN: }
+; PLAIN: define i64 @fc() nounwind {
+; PLAIN:   %t = bitcast i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2) to i64
+; PLAIN:   ret i64 %t
+; PLAIN: }
+; PLAIN: define i64 @fd() nounwind {
+; PLAIN:   %t = bitcast i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 11) to i64
+; PLAIN:   ret i64 %t
+; PLAIN: }
+; PLAIN: define i64 @fe() nounwind {
+; PLAIN:   %t = bitcast i64 ptrtoint (double* getelementptr (%1* null, i64 0, i32 2) to i64) to i64
+; PLAIN:   ret i64 %t
+; PLAIN: }
+; PLAIN: define i64 @ff() nounwind {
+; PLAIN:   %t = bitcast i64 1 to i64
+; PLAIN:   ret i64 %t
+; PLAIN: }
+; OPT: define i64 @fa() nounwind {
+; OPT:   ret i64 mul (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2310)
+; OPT: }
+; OPT: define i64 @fb() nounwind {
+; OPT:   ret i64 ptrtoint (double* getelementptr (%0* null, i64 0, i32 1) to i64)
+; OPT: }
+; OPT: define i64 @fc() nounwind {
+; OPT:   ret i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2)
+; OPT: }
+; OPT: define i64 @fd() nounwind {
+; OPT:   ret i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 11)
+; OPT: }
+; OPT: define i64 @fe() nounwind {
+; OPT:   ret i64 ptrtoint (double* getelementptr (%1* null, i64 0, i32 2) to i64)
+; OPT: }
+; OPT: define i64 @ff() nounwind {
+; OPT:   ret i64 1
+; OPT: }
+; TO: define i64 @fa() nounwind {
+; TO:   ret i64 18480
+; TO: }
+; TO: define i64 @fb() nounwind {
+; TO:   ret i64 8
+; TO: }
+; TO: define i64 @fc() nounwind {
+; TO:   ret i64 16
+; TO: }
+; TO: define i64 @fd() nounwind {
+; TO:   ret i64 88
+; TO: }
+; TO: define i64 @fe() nounwind {
+; TO:   ret i64 16
+; TO: }
+; TO: define i64 @ff() nounwind {
+; TO:   ret i64 1
+; TO: }
+; SCEV: Classifying expressions for: @fa
+; SCEV:   %t = bitcast i64 mul (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2310) to i64 
+; SCEV:   -->  (2310 * sizeof(double))
+; SCEV: Classifying expressions for: @fb
+; SCEV:   %t = bitcast i64 ptrtoint (double* getelementptr (%0* null, i64 0, i32 1) to i64) to i64 
+; SCEV:   -->  alignof(double)
+; SCEV: Classifying expressions for: @fc
+; SCEV:   %t = bitcast i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 2) to i64 
+; SCEV:   -->  (2 * sizeof(double))
+; SCEV: Classifying expressions for: @fd
+; SCEV:   %t = bitcast i64 mul nuw (i64 ptrtoint (double* getelementptr (double* null, i32 1) to i64), i64 11) to i64 
+; SCEV:   -->  (11 * sizeof(double))
+; SCEV: Classifying expressions for: @fe
+; SCEV:   %t = bitcast i64 ptrtoint (double* getelementptr (%1* null, i64 0, i32 2) to i64) to i64 
+; SCEV:   -->  offsetof({ double, float, double, double }, 2)
+; SCEV: Classifying expressions for: @ff
+; SCEV:   %t = bitcast i64 1 to i64 
+; SCEV:   -->  1
+
+define i64 @fa() nounwind {
+  %t = bitcast i64 mul (i64 3, i64 mul (i64 ptrtoint ({[7 x double], [7 x double]}* getelementptr ({[7 x double], [7 x double]}* null, i64 11) to i64), i64 5)) to i64
+  ret i64 %t
+}
+define i64 @fb() nounwind {
+  %t = bitcast i64 ptrtoint ([13 x double]* getelementptr ({i1, [13 x double]}* null, i64 0, i32 1) to i64) to i64
+  ret i64 %t
+}
+define i64 @fc() nounwind {
+  %t = bitcast i64 ptrtoint (double* getelementptr ({double, double, double, double}* null, i64 0, i32 2) to i64) to i64
+  ret i64 %t
+}
+define i64 @fd() nounwind {
+  %t = bitcast i64 ptrtoint (double* getelementptr ([13 x double]* null, i64 0, i32 11) to i64) to i64
+  ret i64 %t
+}
+define i64 @fe() nounwind {
+  %t = bitcast i64 ptrtoint (double* getelementptr ({double, float, double, double}* null, i64 0, i32 2) to i64) to i64
+  ret i64 %t
+}
+define i64 @ff() nounwind {
+  %t = bitcast i64 ptrtoint (<{ i16, i128 }>* getelementptr ({i1, <{ i16, i128 }>}* null, i64 0, i32 1) to i64) to i64
+  ret i64 %t
+}
+
+; PLAIN: define i64* @fM() nounwind {
+; PLAIN:   %t = bitcast i64* getelementptr (i64* null, i32 1) to i64*
+; PLAIN:   ret i64* %t
+; PLAIN: }
+; PLAIN: define i64* @fN() nounwind {
+; PLAIN:   %t = bitcast i64* getelementptr (%2* null, i32 0, i32 1) to i64*
+; PLAIN:   ret i64* %t
+; PLAIN: }
+; PLAIN: define i64* @fO() nounwind {
+; PLAIN:   %t = bitcast i64* getelementptr ([2 x i64]* null, i32 0, i32 1) to i64*
+; PLAIN:   ret i64* %t
+; PLAIN: }
+; OPT: define i64* @fM() nounwind {
+; OPT:   ret i64* getelementptr (i64* null, i32 1)
+; OPT: }
+; OPT: define i64* @fN() nounwind {
+; OPT:   ret i64* getelementptr (%2* null, i32 0, i32 1)
+; OPT: }
+; OPT: define i64* @fO() nounwind {
+; OPT:   ret i64* getelementptr ([2 x i64]* null, i32 0, i32 1)
+; OPT: }
+; TO: define i64* @fM() nounwind {
+; TO:   ret i64* inttoptr (i64 8 to i64*)
+; TO: }
+; TO: define i64* @fN() nounwind {
+; TO:   ret i64* inttoptr (i64 8 to i64*)
+; TO: }
+; TO: define i64* @fO() nounwind {
+; TO:   ret i64* inttoptr (i64 8 to i64*)
+; TO: }
+; SCEV: Classifying expressions for: @fM
+; SCEV:   %t = bitcast i64* getelementptr (i64* null, i32 1) to i64* 
+; SCEV:   -->  sizeof(i64)
+; SCEV: Classifying expressions for: @fN
+; SCEV:   %t = bitcast i64* getelementptr (%2* null, i32 0, i32 1) to i64* 
+; SCEV:   -->  sizeof(i64)
+; SCEV: Classifying expressions for: @fO
+; SCEV:   %t = bitcast i64* getelementptr ([2 x i64]* null, i32 0, i32 1) to i64* 
+; SCEV:   -->  sizeof(i64)
+
+define i64* @fM() nounwind {
+  %t = bitcast i64* getelementptr (i64 *null, i32 1) to i64*
+  ret i64* %t
+}
+define i64* @fN() nounwind {
+  %t = bitcast i64* getelementptr ({ i64, i64 } *null, i32 0, i32 1) to i64*
+  ret i64* %t
+}
+define i64* @fO() nounwind {
+  %t = bitcast i64* getelementptr ([2 x i64] *null, i32 0, i32 1) to i64*
+  ret i64* %t
 }