[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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287099 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/Mips/MipsFastISel.cpp b/lib/Target/Mips/MipsFastISel.cpp
index 895d0f7..cfce60c 100644 (file)
--- a/lib/Target/Mips/MipsFastISel.cpp
+++ b/lib/Target/Mips/MipsFastISel.cpp
@@ -438,7 +438,7 @@ bool MipsFastISel::computeAddress(const Value *Obj, Address &Addr) {
   }
   case Instruction::GetElementPtr: {
     Address SavedAddr = Addr;
-    uint64_t TmpOffset = Addr.getOffset();
+    int64_t TmpOffset = Addr.getOffset();
     // Iterate through the GEP folding the constants into offsets where
     // we can.
     gep_type_iterator GTI = gep_type_begin(U);
@@ -756,7 +756,7 @@ bool MipsFastISel::emitLoad(MVT VT, unsigned &ResultReg, Address &Addr,
   if (Addr.isFIBase()) {
     unsigned FI = Addr.getFI();
     unsigned Align = 4;
-    unsigned Offset = Addr.getOffset();
+    int64_t Offset = Addr.getOffset();
     MachineFrameInfo &MFI = MF->getFrameInfo();
     MachineMemOperand *MMO = MF->getMachineMemOperand(
         MachinePointerInfo::getFixedStack(*MF, FI), MachineMemOperand::MOLoad,
@@ -807,7 +807,7 @@ bool MipsFastISel::emitStore(MVT VT, unsigned SrcReg, Address &Addr,
   if (Addr.isFIBase()) {
     unsigned FI = Addr.getFI();
     unsigned Align = 4;
-    unsigned Offset = Addr.getOffset();
+    int64_t Offset = Addr.getOffset();
     MachineFrameInfo &MFI = MF->getFrameInfo();
     MachineMemOperand *MMO = MF->getMachineMemOperand(
         MachinePointerInfo::getFixedStack(*MF, FI), MachineMemOperand::MOStore,

diff --git a/test/CodeGen/Mips/Fast-ISel/stackloadstore.ll b/test/CodeGen/Mips/Fast-ISel/stackloadstore.ll
new file mode 100644 (file)
index 0000000..421f8ff
--- /dev/null
+++ b/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
+}