From f401069962f9c65b23467eda3ba990b2afbaad27 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 17 Oct 2024 20:17:56 +0200
Subject: [PATCH] s390x: Hard code the link register for ElfTlsGetOffset
 (#9361)

* s390x: Hard code the link register for ElfTlsGetOffset

The ElfTlsGetOffset pseudo-instruction already hard codes the rest of
the abi anyway and if another abi is ever needed, adding another
pseudo-instruction or an enum field to the existing one would likely be
necessary anyway.

* Remove a couple of dead_code allows
---
 cranelift/bforest/src/node.rs                  |  1 -
 cranelift/codegen/src/isa/riscv64/inst/imms.rs |  1 -
 cranelift/codegen/src/isa/s390x/inst.isle      |  1 -
 cranelift/codegen/src/isa/s390x/inst/emit.rs   |  6 ++----
 cranelift/codegen/src/isa/s390x/inst/mod.rs    | 12 +++---------
 cranelift/codegen/src/isa/s390x/lower.isle     |  2 +-
 6 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/cranelift/bforest/src/node.rs b/cranelift/bforest/src/node.rs
index 443c112ed888..848c657e82c8 100644
--- a/cranelift/bforest/src/node.rs
+++ b/cranelift/bforest/src/node.rs
@@ -13,7 +13,6 @@ use core::fmt;
 ///
 /// An inner node contains at least M/2 node references unless it is the right-most node at its
 /// level. A leaf node contains at least N/2 keys unless it is the right-most leaf.
-#[allow(dead_code)] // workaround for https://github.com/rust-lang/rust/issues/64362
 pub(super) enum NodeData<F: Forest> {
     Inner {
         /// The number of keys in this node.
diff --git a/cranelift/codegen/src/isa/riscv64/inst/imms.rs b/cranelift/codegen/src/isa/riscv64/inst/imms.rs
index 28f279154eaa..8f53506ce049 100644
--- a/cranelift/codegen/src/isa/riscv64/inst/imms.rs
+++ b/cranelift/codegen/src/isa/riscv64/inst/imms.rs
@@ -2,7 +2,6 @@
 
 // Some variants are never constructed, but we still want them as options in the future.
 use super::Inst;
-#[allow(dead_code)]
 use std::fmt::{Debug, Display, Formatter, Result};
 
 #[derive(Copy, Clone, Debug, Default)]
diff --git a/cranelift/codegen/src/isa/s390x/inst.isle b/cranelift/codegen/src/isa/s390x/inst.isle
index 342f5846fddb..173cb7bd28a5 100644
--- a/cranelift/codegen/src/isa/s390x/inst.isle
+++ b/cranelift/codegen/src/isa/s390x/inst.isle
@@ -1020,7 +1020,6 @@
       (tls_offset WritableReg)
       (got Reg)
       (got_offset Reg)
-      (link WritableReg)
       (symbol BoxSymbolReloc))
 ))
 
diff --git a/cranelift/codegen/src/isa/s390x/inst/emit.rs b/cranelift/codegen/src/isa/s390x/inst/emit.rs
index eb42cc15a9ab..24bd4cb0fcfc 100644
--- a/cranelift/codegen/src/isa/s390x/inst/emit.rs
+++ b/cranelift/codegen/src/isa/s390x/inst/emit.rs
@@ -3250,9 +3250,7 @@ impl Inst {
                 put(sink, &enc_rr(opcode, gpr(15), rn));
                 sink.add_call_site();
             }
-            &Inst::ElfTlsGetOffset {
-                ref symbol, link, ..
-            } => {
+            &Inst::ElfTlsGetOffset { ref symbol, .. } => {
                 let opcode = 0xc05; // BRASL
 
                 // Add relocation for target function. This has to be done
@@ -3265,7 +3263,7 @@ impl Inst {
                     _ => unreachable!(),
                 }
 
-                put(sink, &enc_ril_b(opcode, link.to_reg(), 0));
+                put(sink, &enc_ril_b(opcode, gpr(14), 0));
                 sink.add_call_site();
             }
             &Inst::Args { .. } => {}
diff --git a/cranelift/codegen/src/isa/s390x/inst/mod.rs b/cranelift/codegen/src/isa/s390x/inst/mod.rs
index 65c5d52ec044..75e7daab707f 100644
--- a/cranelift/codegen/src/isa/s390x/inst/mod.rs
+++ b/cranelift/codegen/src/isa/s390x/inst/mod.rs
@@ -923,7 +923,6 @@ fn s390x_get_operands(inst: &mut Inst, collector: &mut DenyReuseVisitor<impl Ope
             tls_offset,
             got,
             got_offset,
-            link,
             ..
         } => {
             collector.reg_fixed_use(got, gpr(12));
@@ -931,7 +930,7 @@ fn s390x_get_operands(inst: &mut Inst, collector: &mut DenyReuseVisitor<impl Ope
             collector.reg_fixed_def(tls_offset, gpr(2));
 
             let mut clobbers = S390xMachineDeps::get_regs_clobbered_by_call(CallConv::SystemV);
-            clobbers.add(link.to_reg().to_real_reg().unwrap().into());
+            clobbers.add(gpr_preg(14));
             clobbers.remove(gpr_preg(2));
             collector.reg_clobbers(clobbers);
         }
@@ -3164,19 +3163,14 @@ impl Inst {
                 };
                 format!("return_call_ind {rn}{callee_pop_size}")
             }
-            &Inst::ElfTlsGetOffset {
-                ref symbol,
-                ref link,
-                ..
-            } => {
-                let link = link.to_reg();
+            &Inst::ElfTlsGetOffset { ref symbol, .. } => {
                 let dest = match &**symbol {
                     SymbolReloc::TlsGd { name } => {
                         format!("tls_gdcall:{}", name.display(None))
                     }
                     _ => unreachable!(),
                 };
-                format!("brasl {}, {}", show_reg(link), dest)
+                format!("brasl {}, {}", show_reg(gpr(14)), dest)
             }
             &Inst::Args { ref args } => {
                 let mut s = "args".to_string();
diff --git a/cranelift/codegen/src/isa/s390x/lower.isle b/cranelift/codegen/src/isa/s390x/lower.isle
index 225918a22bac..1b21021f0ff2 100644
--- a/cranelift/codegen/src/isa/s390x/lower.isle
+++ b/cranelift/codegen/src/isa/s390x/lower.isle
@@ -2279,7 +2279,7 @@
 (rule (lib_call_tls_get_offset got got_offset symbol)
       (let ((tls_offset WritableReg (temp_writable_reg $I64))
             (_ Unit (abi_for_elf_tls_get_offset))
-            (_ Unit (emit (MInst.ElfTlsGetOffset tls_offset got got_offset (writable_link_reg) symbol))))
+            (_ Unit (emit (MInst.ElfTlsGetOffset tls_offset got got_offset symbol))))
         tls_offset))
 
 (decl abi_for_elf_tls_get_offset () Unit)