> Date: Mon, 25 Dec 2017 00:52:56 +0100
> From: Patrick Wildt <patr...@blueri.se>
>
> Hi,
>
> gerhard@ found a bug in LLVM's i386 code. He noticed that some floating
> point instructions were "optimized" and thus reordered between other FP
> instructions that changed floating point modes, so that those reordered
> instructions were running with an incorrent mode.
>
> I don't completely grasp the internals, but it looks someone at LLVM
> took care of my bug report and changed some pseudo memory instructions
> to have side effects, so that they aren't reordered. This has fixed
> our test case.
>
> https://github.com/llvm-mirror/llvm/commit/63029e5caea7ef0af525e4f66249ca7ffa7e1280
>
> ok?
Sure. Wonder if that will end up in a 5.0.2 release at some point...
> diff --git a/gnu/llvm/lib/Target/X86/X86InstrFPStack.td
> b/gnu/llvm/lib/Target/X86/X86InstrFPStack.td
> index 11b1d070ef2..fb7eb87c64d 100644
> --- 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 {
>
>
