[PATCH] D112143: [X86][ABI] Do not return float/double from x87 registers when x87 is disabled

[Pengfei Wang via Phabricator via cfe-commits]

pengfei created this revision.
pengfei added reviewers: aturetsk, echristo, RKSimon, LuoYuanke, craig.topper.
Herald added subscribers: dang, hiraditya.
pengfei requested review of this revision.
Herald added projects: clang, LLVM.
Herald added subscribers: llvm-commits, cfe-commits.

This is aligned with GCC's behavior.
Also, alias `-mno-fp-ret-in-387` to `-mno-x87`, by which we can fix pr51498.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D112143

Files:
  clang/include/clang/Driver/Options.td
  clang/test/Driver/x86-target-features.c
  llvm/lib/Target/X86/X86CallingConv.td
  llvm/test/CodeGen/X86/no-x87.ll


Index: llvm/test/CodeGen/X86/no-x87.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/no-x87.ll
@@ -0,0 +1,17 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=i686-- | FileCheck %s -check-prefix=X87
+; RUN: llc < %s -mtriple=i686-- -mattr=-x87 | FileCheck %s -check-prefix=NOX87
+
+define float @foo(float %a, float %b) nounwind {
+; X87-LABEL: foo:
+; X87:       # %bb.0: # %entry
+; X87-NEXT:    flds {{[0-9]+}}(%esp)
+; X87-NEXT:    retl
+;
+; NOX87-LABEL: foo:
+; NOX87:       # %bb.0: # %entry
+; NOX87-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; NOX87-NEXT:    retl
+entry:
+  ret float %b
+}
Index: llvm/lib/Target/X86/X86CallingConv.td
===================================================================
--- llvm/lib/Target/X86/X86CallingConv.td
+++ llvm/lib/Target/X86/X86CallingConv.td
@@ -273,6 +273,10 @@
   // conv.
   CCIfInReg<CCIfSubtarget<"hasSSE2()",
     CCIfType<[f32, f64], CCAssignToReg<[XMM0,XMM1,XMM2]>>>>,
+  CCIfNotSubtarget<"hasX87()",
+    CCIfType<[f32], CCAssignToReg<[AX, DX, CX]>>>,
+  CCIfNotSubtarget<"hasX87()",
+    CCIfType<[f64], CCAssignToReg<[EAX, EDX, ECX]>>>,
   CCIfType<[f32,f64], CCAssignToReg<[FP0, FP1]>>,
   CCIfType<[f16], CCAssignToReg<[XMM0,XMM1,XMM2]>>,
   CCDelegateTo<RetCC_X86Common>
Index: clang/test/Driver/x86-target-features.c
===================================================================
--- clang/test/Driver/x86-target-features.c
+++ clang/test/Driver/x86-target-features.c
@@ -2,6 +2,7 @@
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-x87 %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-X87 %s
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -m80387 %s -### -o %t.o 2>&1 | FileCheck -check-prefix=X87 %s
 // RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-80387 %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-X87 %s
+// RUN: %clang -target i386-unknown-linux-gnu -march=i386 -mno-fp-ret-in-387 %s -### -o %t.o 2>&1 | FileCheck -check-prefix=NO-X87 %s
 // X87: "-target-feature" "+x87"
 // NO-X87: "-target-feature" "-x87"
 
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -4166,6 +4166,7 @@
 def mno_x87 : Flag<["-"], "mno-x87">, Group<m_x86_Features_Group>;
 def m80387 : Flag<["-"], "m80387">, Alias<mx87>;
 def mno_80387 : Flag<["-"], "mno-80387">, Alias<mno_x87>;
+def mno_fp_ret_in_387 : Flag<["-"], "mno-fp-ret-in-387">, Alias<mno_x87>;
 def mmmx : Flag<["-"], "mmmx">, Group<m_x86_Features_Group>;
 def mno_mmx : Flag<["-"], "mno-mmx">, Group<m_x86_Features_Group>;
 def m3dnow : Flag<["-"], "m3dnow">, Group<m_x86_Features_Group>;


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