[AMDGPU] Suppress DataLayout warnings after recent change

Summary:
Recent changes caused all AMDGPU toolchain programs to emit unhelpful
warnings since we linke a lot of external libraries. For now just accept
the old triple without warnings. We can probably remove this in the
future when these get updated.

Author: jhuber6

llvm/lib/Linker/IRMover.cpp

@@ -1489,6 +1489,13 @@ Error IRLinker::run() {
                                   SrcTriple.getOSName() == "unknown");
     EnableTripleWarning = !SrcHasLibDeviceTriple;
     EnableDLWarning = !(SrcHasLibDeviceTriple && SrcHasLibDeviceDL);
+  } else if (SrcTriple.isAMDGPU() && DstTriple.isAMDGPU()) {
+    StringRef SrcDL = SrcM->getDataLayoutStr();
+    StringRef DstDL = DstM.getDataLayoutStr();
+
+    // Suppress the data layout warning if the old layout without ELF mangling
+    // specified is used.
+    EnableDLWarning = DstDL.drop_front(4) != SrcDL;
   }
 
   if (EnableDLWarning && (SrcM->getDataLayout() != DstM.getDataLayout())) {

llvm/test/Linker/Inputs/legacy-amdgcn.ll

@@ -0,0 +1,2 @@
+target datalayout = "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128:128:48-p9:192:256:256:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8:9"
+target triple = "amdgcn-amd-amdhsa"

llvm/test/Linker/amdgcn-triple.ll

@@ -0,0 +1,6 @@
+; RUN: llvm-link %s %S/Inputs/legacy-amdgcn.ll -S -o - 2>&1 | FileCheck %s
+
+; CHECK-NOT: Linking two modules of different data layouts
+; CHECK: target triple = "amdgcn-amd-amdhsa"
+target datalayout = "e-m:e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128:128:48-p9:192:256:256:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8:9"
+target triple = "amdgcn-amd-amdhsa"