[llvm] [AMDPGU] Auto-upgrade ELF mangling in the data layout (PR #163644)

[Shilei Tian via llvm-commits]

================
@@ -6055,35 +6054,43 @@ std::string llvm::UpgradeDataLayoutString(StringRef DL, StringRef TT) {
     return DL.str();
   }
 
+  // AMDGPU data layout upgrades.
   std::string Res = DL.str();
-  // AMDGCN data layout upgrades.
-  if (T.isAMDGCN()) {
+  if (T.isAMDGPU()) {
     // Define address spaces for constants.
     if (!DL.contains("-G") && !DL.starts_with("G"))
       Res.append(Res.empty() ? "G1" : "-G1");
 
-    // Add missing non-integral declarations.
-    // This goes before adding new address spaces to prevent incoherent string
-    // values.
-    if (!DL.contains("-ni") && !DL.starts_with("ni"))
-      Res.append("-ni:7:8:9");
-    // Update ni:7 to ni:7:8:9.
-    if (DL.ends_with("ni:7"))
-      Res.append(":8:9");
-    if (DL.ends_with("ni:7:8"))
-      Res.append(":9");
-
-    // Add sizing for address spaces 7 and 8 (fat raw buffers and buffer
-    // resources) An empty data layout has already been upgraded to G1 by now.
-    if (!DL.contains("-p7") && !DL.starts_with("p7"))
-      Res.append("-p7:160:256:256:32");
-    if (!DL.contains("-p8") && !DL.starts_with("p8"))
-      Res.append("-p8:128:128:128:48");
-    constexpr StringRef OldP8("-p8:128:128-");
-    if (DL.contains(OldP8))
-      Res.replace(Res.find(OldP8), OldP8.size(), "-p8:128:128:128:48-");
-    if (!DL.contains("-p9") && !DL.starts_with("p9"))
-      Res.append("-p9:192:256:256:32");
+    // AMDGCN data layout upgrades.
+    if (T.isAMDGCN()) {
+
+      // Add missing non-integral declarations.
+      // This goes before adding new address spaces to prevent incoherent string
+      // values.
+      if (!DL.contains("-ni") && !DL.starts_with("ni"))
+        Res.append("-ni:7:8:9");
+      // Update ni:7 to ni:7:8:9.
+      if (DL.ends_with("ni:7"))
+        Res.append(":8:9");
+      if (DL.ends_with("ni:7:8"))
+        Res.append(":9");
+
+      // Add sizing for address spaces 7 and 8 (fat raw buffers and buffer
+      // resources) An empty data layout has already been upgraded to G1 by now.
+      if (!DL.contains("-p7") && !DL.starts_with("p7"))
+        Res.append("-p7:160:256:256:32");
+      if (!DL.contains("-p8") && !DL.starts_with("p8"))
+        Res.append("-p8:128:128:128:48");
+      constexpr StringRef OldP8("-p8:128:128-");
+      if (DL.contains(OldP8))
+        Res.replace(Res.find(OldP8), OldP8.size(), "-p8:128:128:128:48-");
+      if (!DL.contains("-p9") && !DL.starts_with("p9"))
+        Res.append("-p9:192:256:256:32");
+    }
+
+    // Upgrade the ELF mangling mode.
+    if (!DL.starts_with("e-m:"))
----------------
shiltian wrote:

why not `contains`, like what others are doing, but assert this will be the start?

https://github.com/llvm/llvm-project/pull/163644