Struct byval: use the correct alignment for loads generated to load

from struct byval to registers.

We used to pass 0 which means the alignment of PtrVT. Even when the alignment
of the struct is smaller than 4, the LOADs would have alignment of 4, and
further optimizations could combine the LOADs into a ldm, which would
cause crash.

The fix is to pass the alignment of the struct byval.

rdar://problem/15144402

llvm-svn: 192126

2 files changed, 29 insertions, 1 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index c1ed4a64283..03ca1999b8e 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -1570,7 +1570,8 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
           SDValue AddArg = DAG.getNode(ISD::ADD, dl, PtrVT, Arg, Const);
           SDValue Load = DAG.getLoad(PtrVT, dl, Chain, AddArg,
                                      MachinePointerInfo(),
-                                     false, false, false, 0);
+                                     false, false, false,
+                                     DAG.InferPtrAlignment(AddArg));
           MemOpChains.push_back(Load.getValue(1));
           RegsToPass.push_back(std::make_pair(j, Load));
         }
diff --git a/llvm/test/CodeGen/ARM/byval_load_align.ll b/llvm/test/CodeGen/ARM/byval_load_align.ll
new file mode 100644
index 00000000000..2c0910c71d2
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/byval_load_align.ll
@@ -0,0 +1,27 @@
+; RUN: llc < %s -mtriple thumbv7-apple-ios -O1 | FileCheck %s
+
+; rdar://15144402
+; Make sure we don't assume 4-byte alignment when loading from a byval argument
+; with alignment of 2.
+; CHECK: ldr r1, [r[[REG:[0-9]+]]]
+; CHECK: ldr r2, [r[[REG]], #4]
+; CHECK: ldr r3, [r[[REG]], #8]
+; CHECK-NOT: ldm
+; CHECK: .align	1 @ @sID
+
+%struct.ModuleID = type { [32 x i8], [32 x i8], i16 }
+
+@sID = internal constant %struct.ModuleID { [32 x i8] c"TEST\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", [32 x i8] c"1.0\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", i16 23 }, align 2
+
+; Function Attrs: nounwind ssp
+define void @Client() #0 {
+entry:
+  tail call void @Logger(i8 signext 97, %struct.ModuleID* byval @sID) #2
+  ret void
+}
+
+declare void @Logger(i8 signext, %struct.ModuleID* byval) #1
+
+attributes #0 = { nounwind ssp "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind }