Cherry-pick a change from LLVM that marks specific pseudo memory

instructions to have side effects so the optimizer does not reorder
them across fnstcw/fldcw sequences.  Fixes a bug seen in sqlite3 on
i386.

ok kettenis@

diff --git a/gnu/llvm/lib/Target/X86/X86InstrFPStack.td b/gnu/llvm/lib/Target/X86/X86InstrFPStack.td
index 11b1d07..fb7eb87 100644 (file)
--- a/gnu/llvm/lib/Target/X86/X86InstrFPStack.td
+++ b/gnu/llvm/lib/Target/X86/X86InstrFPStack.td
@@ -139,6 +139,7 @@ def _Fp80 : FpI_<(outs RFP80:$dst), (ins RFP80:$src1, RFP80:$src2), TwoArgFP,
 // These instructions cannot address 80-bit memory.
 multiclass FPBinary<SDNode OpNode, Format fp, string asmstring,
                     bit Forward = 1> {
+let mayLoad = 1, hasSideEffects = 1 in {
 // ST(0) = ST(0) + [mem]
 def _Fp32m  : FpIf32<(outs RFP32:$dst),
                      (ins RFP32:$src1, f32mem:$src2), OneArgFPRW,
@@ -175,10 +176,8 @@ def _Fp80m64: FpI_<(outs RFP80:$dst),
                         (OpNode RFP80:$src1, (f80 (extloadf64 addr:$src2)))),
                        (set RFP80:$dst,
                         (OpNode (f80 (extloadf64 addr:$src2)), RFP80:$src1)))]>;
-let mayLoad = 1 in
 def _F32m  : FPI<0xD8, fp, (outs), (ins f32mem:$src),
                  !strconcat("f", asmstring, "{s}\t$src")>;
-let mayLoad = 1 in
 def _F64m  : FPI<0xDC, fp, (outs), (ins f64mem:$src),
                  !strconcat("f", asmstring, "{l}\t$src")>;
 // ST(0) = ST(0) + [memint]
@@ -224,12 +223,11 @@ def _FpI32m80 : FpI_<(outs RFP80:$dst), (ins RFP80:$src1, i32mem:$src2),
                            (OpNode RFP80:$src1, (X86fild addr:$src2, i32))),
                           (set RFP80:$dst,
                            (OpNode (X86fild addr:$src2, i32), RFP80:$src1)))]>;
-let mayLoad = 1 in
 def _FI16m  : FPI<0xDE, fp, (outs), (ins i16mem:$src),
                   !strconcat("fi", asmstring, "{s}\t$src")>;
-let mayLoad = 1 in
 def _FI32m  : FPI<0xDA, fp, (outs), (ins i32mem:$src),
                   !strconcat("fi", asmstring, "{l}\t$src")>;
+} // mayLoad = 1, hasSideEffects = 1
 }
 
 let Defs = [FPSW] in {