[mips] Fix unsigned/signed type error
MipsFastISel uses a a class to represent addresses with a signed member
to represent the offset. MipsFastISel::emitStore, emitLoad and computeAddress
all treated the offset as being positive. In cases where the offset was
actually negative and a frame pointer was used, this would cause the constant
synthesis routine to crash as it would generate an unexpected instruction
sequence when frame indexes are replaced.
Reviewers: vkalintiris
Differential Revision: https://reviews.llvm.org/D26192
llvm-svn: 287099
diff --git a/llvm/test/CodeGen/Mips/Fast-ISel/stackloadstore.ll b/llvm/test/CodeGen/Mips/Fast-ISel/stackloadstore.ll
new file mode 100644
index 0000000..421f8ff
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/Fast-ISel/stackloadstore.ll
@@ -0,0 +1,18 @@
+; RUN: llc < %s -march=mipsel -mcpu=mips32 -fast-isel -disable-fp-elim -relocation-model=pic < %s
+
+; Test that negative array access don't crash constant synthesis when fast isel
+; generates negative offsets.
+
+define i16 @test() {
+ %a = alloca [4 x i16], align 4
+ %arrayidx = getelementptr inbounds [4 x i16], [4 x i16]* %a, i32 0, i32 -2
+ %b = load i16, i16* %arrayidx, align 2
+ ret i16 %b
+}
+
+define void @test2() {
+ %a = alloca [4 x i16], align 4
+ %arrayidx = getelementptr inbounds [4 x i16], [4 x i16]* %a, i32 0, i32 -2
+ store i16 2, i16* %arrayidx, align 2
+ ret void
+}