[PATCH] D70465: [Win64] Handle FP arguments more gracefully under -mno-sse

[Reid Kleckner via Phabricator via llvm-commits]

rnk created this revision.
rnk added reviewers: jyknight, aemerson.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

This falls back to passing them via x87. This doesn't follow any
particular ABI, and should of course be considered unstable.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D70465

Files:
  llvm/lib/Target/X86/X86CallingConv.td
  llvm/test/CodeGen/X86/no-sse-win64.ll


Index: llvm/test/CodeGen/X86/no-sse-win64.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/no-sse-win64.ll
@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=x86_64-windows-msvc < %s | FileCheck %s -check-prefix=SSE
+; RUN: llc -mtriple=x86_64-windows-msvc < %s -mattr=-sse | FileCheck %s -check-prefix=NOSSE
+
+define void @pass_double(double %v, double* %p) {
+; SSE-LABEL: pass_double:
+; SSE:       # %bb.0:
+; SSE-NEXT:    movsd %xmm0, (%rdx)
+; SSE-NEXT:    retq
+;
+; NOSSE-LABEL: pass_double:
+; NOSSE:       # %bb.0:
+; NOSSE-NEXT:    fldl {{[0-9]+}}(%rsp)
+; NOSSE-NEXT:    fstpl (%rcx)
+; NOSSE-NEXT:    retq
+  store double %v, double* %p
+  ret void
+}
+
+define void @pass_float(float %v, float* %p) {
+; SSE-LABEL: pass_float:
+; SSE:       # %bb.0:
+; SSE-NEXT:    movss %xmm0, (%rdx)
+; SSE-NEXT:    retq
+;
+; NOSSE-LABEL: pass_float:
+; NOSSE:       # %bb.0:
+; NOSSE-NEXT:    flds {{[0-9]+}}(%rsp)
+; NOSSE-NEXT:    fstps (%rcx)
+; NOSSE-NEXT:    retq
+  store float %v, float* %p
+  ret void
+}
Index: llvm/lib/Target/X86/X86CallingConv.td
===================================================================
--- llvm/lib/Target/X86/X86CallingConv.td
+++ llvm/lib/Target/X86/X86CallingConv.td
@@ -613,7 +613,6 @@
   // 128 bit vectors are passed by pointer
   CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64], CCPassIndirect<i64>>,
 
-
   // 256 bit vectors are passed by pointer
   CCIfType<[v32i8, v16i16, v8i32, v4i64, v8f32, v4f64], CCPassIndirect<i64>>,
 
@@ -644,9 +643,10 @@
                                           [XMM0, XMM1, XMM2, XMM3]>>,
 
   // The first 4 FP/Vector arguments are passed in XMM registers.
-  CCIfType<[f32, f64, v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
-           CCAssignToRegWithShadow<[XMM0, XMM1, XMM2, XMM3],
-                                   [RCX , RDX , R8  , R9  ]>>,
+  CCIfType<[f32, f64],
+           CCIfSubtarget<"hasSSE1()",
+             CCAssignToRegWithShadow<[XMM0, XMM1, XMM2, XMM3],
+                                     [RCX , RDX , R8  , R9  ]>>>,
 
   // Integer/FP values get stored in stack slots that are 8 bytes in size and
   // 8-byte aligned if there are no more registers to hold them.


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