fatal error: error in backend: Cannot select: t3: i32 = fp_to_sint nofpexcept t2

[pkubaj]

Bugzilla Link	46291
Resolution	WONTFIX
Resolved on	Jun 17, 2020 09:28
Version	10.0
OS	FreeBSD
Blocks	#44654
CC	@adalava,@DimitryAndric,@tstellar

Extended Description

FreeBSD head, powerpc64 elfv2 or powerpc or powerpcspe, LLVM 10.0.1-rc1

Reproduction:
pkubaj@talos:$/usr/home/pkubaj/libretro-fbneo$ /usr/bin/cc -cc1 -triple powerpc64-unknown-freebsd13.0 -emit-obj -frounding-math ym2612-5de3af.c
ym2612-5de3af.c:1:1: warning: type specifier missing, defaults to 'int'
a;
^
ym2612-5de3af.c:3:1: warning: type specifier missing, defaults to 'int'
c() { a = b; }
^
ym2612-5de3af.c:3:14: warning: non-void function does not return a value
c() { a = b; }
^
fatal error: error in backend: Cannot select: t3: i32 = fp_to_sint nofpexcept t2
t2: f64,ch = CopyFromReg t0, Register:f64 %5
t1: f64 = Register %5
In function: c

Test case:
a;
double b;
c() { a = b; }

[pkubaj]

It builds without -frounding-math.

[llvmbot]

This is the IR:

@​b = global double 0.000000e+00, align 8
@​a = global i32 0, align 4

; Function Attrs: noinline nounwind optnone strictfp
define signext i32 @​c() #​0 {
entry:
%retval = alloca i32, align 4
%0 = load double, double* @​b, align 8
%conv = call i32 @​llvm.experimental.constrained.fptosi.i32.f64(double %0, metadata !"fpexcept.ignore") #​2
store i32 %conv, i32* @​a, align 4
%1 = load i32, i32* %retval, align 4
ret i32 %1
}

; Function Attrs: inaccessiblememonly nounwind willreturn
declare i32 @​llvm.experimental.constrained.fptosi.i32.f64(double, metadata) #​1

And it has been fixed in https://reviews.llvm.org/D81537

[pkubaj]

Could you then merge it to 10.0.1?

[llvmbot]

I see that you are trying to enable the strict-fp with option -frounding-math for PowerPC on LLVM 10.0.1. As far as I know, PowerPC backend didn't fully support the strict-fp on LLVM 10.0.1, though we are actively adding it and hope to complete it in this Release. That means, even with this patch backport, you might have other issues if with option -frounding-math. Do you still want us to do that ?

[pkubaj]

I see that you are trying to enable the strict-fp with option
-frounding-math for PowerPC on LLVM 10.0.1. As far as I know, PowerPC
backend didn't fully support the strict-fp on LLVM 10.0.1, though we are
actively adding it and hope to complete it in this Release. That means, even
with this patch backport, you might have other issues if with option
-frounding-math. Do you still want us to do that ?

Well, I guess it's ok then as it is. Thanks!