Add comment: data_layout

Author: hegza

compiler/rustc_target/src/spec/targets/riscv32e_unknown_none_elf.rs

@@ -2,6 +2,8 @@ use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, Targ
 
 pub fn target() -> Target {
     Target {
+        // The below `data_layout` is explicitly specified by the ilp32e ABI in LLVM. See also
+        // `options.llvm_abiname`.
         data_layout: "e-m:e-p:32:32-i64:64-n32-S32".into(),
         llvm_target: "riscv32".into(),
         pointer_width: 32,
@@ -11,6 +13,7 @@ pub fn target() -> Target {
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             cpu: "generic-rv32".into(),
+            // The ilp32e ABI specifies the `data_layout`
             llvm_abiname: "ilp32e".into(),
             max_atomic_width: Some(32),
             atomic_cas: false,

compiler/rustc_target/src/spec/targets/riscv32em_unknown_none_elf.rs

@@ -2,6 +2,8 @@ use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, Targ
 
 pub fn target() -> Target {
     Target {
+        // The below `data_layout` is explicitly specified by the ilp32e ABI in LLVM. See also
+        // `options.llvm_abiname`.
         data_layout: "e-m:e-p:32:32-i64:64-n32-S32".into(),
         llvm_target: "riscv32".into(),
         pointer_width: 32,
@@ -11,6 +13,7 @@ pub fn target() -> Target {
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             cpu: "generic-rv32".into(),
+            // The ilp32e ABI specifies the `data_layout`
             llvm_abiname: "ilp32e".into(),
             max_atomic_width: Some(32),
             atomic_cas: false,

compiler/rustc_target/src/spec/targets/riscv32emc_unknown_none_elf.rs

@@ -2,6 +2,8 @@ use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, Targ
 
 pub fn target() -> Target {
     Target {
+        // The below `data_layout` is explicitly specified by the ilp32e ABI in LLVM. See also
+        // `options.llvm_abiname`.
         data_layout: "e-m:e-p:32:32-i64:64-n32-S32".into(),
         llvm_target: "riscv32".into(),
         pointer_width: 32,
@@ -11,6 +13,7 @@ pub fn target() -> Target {
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             cpu: "generic-rv32".into(),
+            // The ilp32e ABI specifies the `data_layout`
             llvm_abiname: "ilp32e".into(),
             max_atomic_width: Some(32),
             atomic_cas: false,