[PowerPC] Correctly compute 64-bit offsets in fast isel

PPCSimplifyAddress contains this code:

  IntegerType *OffsetTy = ((VT == MVT::i32) ? Type::getInt32Ty(*Context)
                                            : Type::getInt64Ty(*Context));

to determine the type to be used for an index register, if one needs
to be created.  However, the "VT" here is the type of the data being
loaded or stored, *not* the type of an address.  This means that if
a data element of type i32 is accessed using an index that does not
not fit into 32 bits, a wrong address is computed here.

Note that PPCFastISel is only ever used on 64-bit currently, so the type
of an address is actually *always* MVT::i64.  Other parts of the code,
even in this same PPCSimplifyAddress routine, already rely on that fact.
Thus, this patch changes the code to simply unconditionally use
Type::getInt64Ty(*Context) as OffsetTy.

llvm-svn: 265023

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/PowerPC/fast-isel-i64offset.ll b/llvm/test/CodeGen/PowerPC/fast-isel-i64offset.ll
new file mode 100644
index 00000000000..e184ce4c3b3
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/fast-isel-i64offset.ll
@@ -0,0 +1,15 @@
+; RUN: llc -mtriple powerpc64-unknown-linux-gnu -fast-isel -O0 < %s | FileCheck %s
+
+; Verify that pointer offsets larger than 32 bits work correctly.
+
+define void @test(i32* %array) {
+; CHECK-LABEL: test:
+; CHECK: lis [[REG:[0-9]+]], 16383
+; CHECK: ori [[REG]], [[REG]], 65535
+; CHECK: sldi [[REG]], [[REG]], 3
+; CHECK: stwx {{[0-9]+}}, 3, [[REG]]
+  %element = getelementptr i32, i32* %array, i64 2147483646
+  store i32 1234, i32* %element
+  ret void
+}
+