cleanup: standardize on summary over index in names

I did this in the user-facing logic, but I noticed while fixing a minor
defect that I had missed it in a few places in the internal details.

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -708,15 +708,15 @@ pub(crate) unsafe fn codegen(
         //   asm from LLVM and use `gcc` to create the object file.
 
         let bc_out = cgcx.output_filenames.temp_path(OutputType::Bitcode, module_name);
-        let bc_index_out =
+        let bc_summary_out =
             cgcx.output_filenames.temp_path(OutputType::ThinLinkBitcode, module_name);
         let obj_out = cgcx.output_filenames.temp_path(OutputType::Object, module_name);
 
         if config.bitcode_needed() {
             let _timer = cgcx
                 .prof
                 .generic_activity_with_arg("LLVM_module_codegen_make_bitcode", &*module.name);
-            let thin = ThinBuffer::new(llmod, config.emit_thin_lto, config.emit_thin_lto_index);
+            let thin = ThinBuffer::new(llmod, config.emit_thin_lto, config.emit_thin_lto_summary);
             let data = thin.data();
 
             if let Some(bitcode_filename) = bc_out.file_name() {
@@ -727,20 +727,20 @@ pub(crate) unsafe fn codegen(
                 );
             }
 
-            if config.emit_thin_lto_index && let Some(thin_link_bitcode_filename) = bc_index_out.file_name() {
-                let index_data = thin.thin_link_data();
+            if config.emit_thin_lto_summary && let Some(thin_link_bitcode_filename) = bc_summary_out.file_name() {
+                let summary_data = thin.thin_link_data();
                 cgcx.prof.artifact_size(
                     "llvm_bitcode_summary",
                     thin_link_bitcode_filename.to_string_lossy(),
-                    index_data.len() as u64,
+                    summary_data.len() as u64,
                 );
 
                 let _timer = cgcx.prof.generic_activity_with_arg(
-                    "LLVM_module_codegen_emit_bitcode_index",
+                    "LLVM_module_codegen_emit_bitcode_summary",
                     &*module.name,
                 );
-                if let Err(err) = fs::write(&bc_index_out, index_data) {
-                    dcx.emit_err(WriteBytecode { path: &bc_index_out, err });
+                if let Err(err) = fs::write(&bc_summary_out, summary_data) {
+                    dcx.emit_err(WriteBytecode { path: &bc_summary_out, err });
                 }
             }
 

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -107,7 +107,7 @@ pub struct ModuleConfig {
     pub emit_asm: bool,
     pub emit_obj: EmitObj,
     pub emit_thin_lto: bool,
-    pub emit_thin_lto_index: bool,
+    pub emit_thin_lto_summary: bool,
     pub bc_cmdline: String,
 
     // Miscellaneous flags. These are mostly copied from command-line
@@ -232,7 +232,7 @@ impl ModuleConfig {
             ),
             emit_obj,
             emit_thin_lto: sess.opts.unstable_opts.emit_thin_lto,
-            emit_thin_lto_index: if_regular!(
+            emit_thin_lto_summary: if_regular!(
                 sess.opts.output_types.contains_key(&OutputType::ThinLinkBitcode),
                 false
             ),
@@ -287,7 +287,7 @@ impl ModuleConfig {
 
     pub fn bitcode_needed(&self) -> bool {
         self.emit_bc
-            || self.emit_thin_lto_index
+            || self.emit_thin_lto_summary
             || self.emit_obj == EmitObj::Bitcode
             || self.emit_obj == EmitObj::ObjectCode(BitcodeSection::Full)
     }