From 461274b81d8641eab64d494accddc81d7db8a09e Mon Sep 17 00:00:00 2001
From: YunQiang Su <syq@debian.org>
Date: Tue, 27 Feb 2024 14:08:36 +0800
Subject: MIPS: Fix asm constraints "f" and "r" for softfloat (#79116)

This include 2 fixes:
        1. Disallow 'f' for softfloat.
        2. Allow 'r' for softfloat.

Currently, 'f' is accpeted by clang, then LLVM meets an internal error.

'r' is rejected by LLVM by: couldn't allocate input reg for constraint
'r'.

Fixes: #64241, #63632

---------

Co-authored-by: Fangrui Song <i@maskray.me>
(cherry picked from commit c88beb4112d5bbf07d76a615ab7f13ba2ba023e6)
---
 clang/lib/Basic/Targets/Mips.h                   |  4 +++-
 clang/test/CodeGen/Mips/inline-asm-constraints.c | 11 +++++++++++
 clang/test/Sema/inline-asm-validate-mips.c       |  9 +++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/CodeGen/Mips/inline-asm-constraints.c
 create mode 100644 clang/test/Sema/inline-asm-validate-mips.c

(limited to 'clang')

diff --git a/clang/lib/Basic/Targets/Mips.h b/clang/lib/Basic/Targets/Mips.h
index f46b95a..23d4e1b 100644
--- a/clang/lib/Basic/Targets/Mips.h
+++ b/clang/lib/Basic/Targets/Mips.h
@@ -237,12 +237,14 @@ public:
     case 'r': // CPU registers.
     case 'd': // Equivalent to "r" unless generating MIPS16 code.
     case 'y': // Equivalent to "r", backward compatibility only.
-    case 'f': // floating-point registers.
     case 'c': // $25 for indirect jumps
     case 'l': // lo register
     case 'x': // hilo register pair
       Info.setAllowsRegister();
       return true;
+    case 'f': // floating-point registers.
+      Info.setAllowsRegister();
+      return FloatABI != SoftFloat;
     case 'I': // Signed 16-bit constant
     case 'J': // Integer 0
     case 'K': // Unsigned 16-bit constant
diff --git a/clang/test/CodeGen/Mips/inline-asm-constraints.c b/clang/test/CodeGen/Mips/inline-asm-constraints.c
new file mode 100644
index 0000000..88afe87
--- /dev/null
+++ b/clang/test/CodeGen/Mips/inline-asm-constraints.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -emit-llvm -triple mips -target-feature +soft-float %s -o - | FileCheck %s --check-prefix=SOFT_FLOAT
+
+// SOFT_FLOAT: call void asm sideeffect "", "r,~{$1}"(float %1)
+void read_float(float *p) {
+  __asm__("" ::"r"(*p));
+}
+
+// SOFT_FLOAT: call void asm sideeffect "", "r,~{$1}"(double %1)
+void read_double(double *p) {
+  __asm__("" :: "r"(*p));
+}
diff --git a/clang/test/Sema/inline-asm-validate-mips.c b/clang/test/Sema/inline-asm-validate-mips.c
new file mode 100644
index 0000000..7da248f
--- /dev/null
+++ b/clang/test/Sema/inline-asm-validate-mips.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple mips64 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple mips64 -target-feature +soft-float -fsyntax-only -verify=softfloat %s
+
+// expected-no-diagnostics
+
+void test_f(float p) {
+  float result = p;
+  __asm__("" :: "f"(result)); // softfloat-error{{invalid input constraint 'f' in asm}}
+}
-- 
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