[llvm] [Sparc] Remove bogus stack adjustment for LD/GD TLS (PR #149890)

[Jessica Clarke via llvm-commits]

https://github.com/jrtc27 updated https://github.com/llvm/llvm-project/pull/149890

>From b3bed761c7ebcd17a40a3e308e32d6e43ca60504 Mon Sep 17 00:00:00 2001
From: Jessica Clarke <jrtc27 at jrtc27.com>
Date: Mon, 21 Jul 2025 20:59:30 +0100
Subject: [PATCH 1/2] [Sparc] Remove bogus stack adjustment for LD/GD TLS

This argument is the number of bytes to adjust the stack by for the
duration of the call. In most cases, PEI is able to eliminate the
corresponding call frame pseudos, folding them into the initial stack
frame allocation (rounded up to stack alignment), where it just ends up
allocating more space than needed. However, in the rare case where this
cannot be done, e.g. due to the use of a dynamic alloca, the 1 byte
stack adjustment persists and results in a misaligned stack for the
duration of the call. This has been the case ever since TLS support was
added in cb1dca602c43 ("[Sparc] Add support for TLS in sparc."), and I
can only assume that 1 was used erroneously thinking that it is the
number of arguments (as there is 1 register argument for the call), not
the number of bytes for on-stack arguments.

Fixes: https://github.com/llvm/llvm-project/issues/149808
---
 llvm/lib/Target/Sparc/SparcISelLowering.cpp | 4 ++--
 llvm/test/CodeGen/SPARC/tls-sp.ll           | 6 +-----
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
index 9b434d87c2676..1aa8efe3e9979 100644
--- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -2201,7 +2201,7 @@ SDValue SparcTargetLowering::LowerGlobalTLSAddress(SDValue Op,
     SDValue Chain = DAG.getEntryNode();
     SDValue InGlue;
 
-    Chain = DAG.getCALLSEQ_START(Chain, 1, 0, DL);
+    Chain = DAG.getCALLSEQ_START(Chain, 0, 0, DL);
     Chain = DAG.getCopyToReg(Chain, DL, SP::O0, Argument, InGlue);
     InGlue = Chain.getValue(1);
     SDValue Callee = DAG.getTargetExternalSymbol("__tls_get_addr", PtrVT);
@@ -2219,7 +2219,7 @@ SDValue SparcTargetLowering::LowerGlobalTLSAddress(SDValue Op,
                      InGlue};
     Chain = DAG.getNode(SPISD::TLS_CALL, DL, NodeTys, Ops);
     InGlue = Chain.getValue(1);
-    Chain = DAG.getCALLSEQ_END(Chain, 1, 0, InGlue, DL);
+    Chain = DAG.getCALLSEQ_END(Chain, 0, 0, InGlue, DL);
     InGlue = Chain.getValue(1);
     SDValue Ret = DAG.getCopyFromReg(Chain, DL, SP::O0, PtrVT, InGlue);
 
diff --git a/llvm/test/CodeGen/SPARC/tls-sp.ll b/llvm/test/CodeGen/SPARC/tls-sp.ll
index 928d1dcbe8300..11325e5f38770 100644
--- a/llvm/test/CodeGen/SPARC/tls-sp.ll
+++ b/llvm/test/CodeGen/SPARC/tls-sp.ll
@@ -29,7 +29,7 @@ define ptr @no_alloca() nounwind {
 ;
 ; SPARC64-LABEL: no_alloca:
 ; SPARC64:       ! %bb.0: ! %entry
-; SPARC64-NEXT:    save %sp, -144, %sp
+; SPARC64-NEXT:    save %sp, -128, %sp
 ; SPARC64-NEXT:  .Ltmp0:
 ; SPARC64-NEXT:    rd %pc, %o7
 ; SPARC64-NEXT:  .Ltmp2:
@@ -62,13 +62,11 @@ define ptr @dynamic_alloca(i64 %n) nounwind {
 ; SPARC-NEXT:  .Ltmp4:
 ; SPARC-NEXT:    or %i0, %lo(_GLOBAL_OFFSET_TABLE_+(.Ltmp4-.Ltmp3)), %i0
 ; SPARC-NEXT:    add %i0, %o7, %i0
-; SPARC-NEXT:    add %sp, -1, %sp
 ; SPARC-NEXT:    sethi %tgd_hi22(x), %i2
 ; SPARC-NEXT:    add %i2, %tgd_lo10(x), %i2
 ; SPARC-NEXT:    add %i0, %i2, %o0, %tgd_add(x)
 ; SPARC-NEXT:    call __tls_get_addr, %tgd_call(x)
 ; SPARC-NEXT:    nop
-; SPARC-NEXT:    add %sp, 1, %sp
 ; SPARC-NEXT:    add %i1, 7, %i0
 ; SPARC-NEXT:    and %i0, -8, %i0
 ; SPARC-NEXT:    sub %sp, %i0, %i0
@@ -88,13 +86,11 @@ define ptr @dynamic_alloca(i64 %n) nounwind {
 ; SPARC64-NEXT:  .Ltmp4:
 ; SPARC64-NEXT:    or %i1, %lo(_GLOBAL_OFFSET_TABLE_+(.Ltmp4-.Ltmp3)), %i1
 ; SPARC64-NEXT:    add %i1, %o7, %i1
-; SPARC64-NEXT:    add %sp, -1, %sp
 ; SPARC64-NEXT:    sethi %tgd_hi22(x), %i2
 ; SPARC64-NEXT:    add %i2, %tgd_lo10(x), %i2
 ; SPARC64-NEXT:    add %i1, %i2, %o0, %tgd_add(x)
 ; SPARC64-NEXT:    call __tls_get_addr, %tgd_call(x)
 ; SPARC64-NEXT:    nop
-; SPARC64-NEXT:    add %sp, 1, %sp
 ; SPARC64-NEXT:    add %i0, 15, %i0
 ; SPARC64-NEXT:    and %i0, -16, %i0
 ; SPARC64-NEXT:    sub %sp, %i0, %i0

>From 3a05fb213b285bc0b3f6d52b4ef2849fbc3e063e Mon Sep 17 00:00:00 2001
From: Jessica Clarke <jrtc27 at jrtc27.com>
Date: Mon, 21 Jul 2025 22:55:14 +0100
Subject: [PATCH 2/2] Remove fixed TODO

---
 llvm/test/CodeGen/SPARC/tls-sp.ll | 2 --
 1 file changed, 2 deletions(-)

diff --git a/llvm/test/CodeGen/SPARC/tls-sp.ll b/llvm/test/CodeGen/SPARC/tls-sp.ll
index 11325e5f38770..de9af01398d23 100644
--- a/llvm/test/CodeGen/SPARC/tls-sp.ll
+++ b/llvm/test/CodeGen/SPARC/tls-sp.ll
@@ -2,8 +2,6 @@
 ; RUN: llc -mtriple=sparc -relocation-model=pic < %s | FileCheck --check-prefix=SPARC %s
 ; RUN: llc -mtriple=sparc64 -relocation-model=pic < %s | FileCheck --check-prefix=SPARC64 %s
 
-;; TODO: Fix the code generation for these functions.
-
 @x = external thread_local global i8
 
 ;; Test that we don't over-allocate stack space when calling __tls_get_addr