Public bug reported:
binary16 float-point arithmetic crashes LLVM on s390x due to the LLVM
backend being unable to lower the LLVM IR to the machine code.
You can find a short reproducer below:
define noundef zeroext i1 @test_func(half noundef %f) unnamed_addr {
start:
%self = fdiv half %f, 0xHC700
%_4 = bitcast half %self to i16
%_0 = icmp slt i16 %_4, 0
ret i1 %_0
}
You can save this LLVM IR text to a file called `test-ir.ll` and build it using
`clang test-ir.ll -c -o test-ir.o` on a s390x device and watch LLVM explodes
with:
warning: overriding the module target triple with s390x-unknown-linux-gnu
[-Woverride-module]
fatal error: error in backend: Cannot select: 0x6005f020ae20: i32 = fp_to_fp16
0x6005f020adb0
0x6005f020adb0: f32 = fdiv 0x6005f020af70, 0x6005f020b4b0
0x6005f020af70: f32 = fp16_to_fp 0x6005f020b520
0x6005f020b520: i32 = fp_to_fp16 0x6005f020a9c0
0x6005f020a9c0: f32,ch = CopyFromReg 0x6005f01e5220, Register:f32 %0
0x6005f020a950: f32 = Register %0
0x6005f020b4b0: f32,ch = load<(load (s32) from constant-pool)>
0x6005f01e5220, 0x6005f020b280, undef:i64
0x6005f020b280: i64 = SystemZISD::PCREL_WRAPPER
TargetConstantPool:i64<float -7.000000e+00> 0
0x6005f020b1a0: i64 = TargetConstantPool<float -7.000000e+00> 0
0x6005f020b130: i64 = undef
In function: test_func
** Affects: ubuntu-z-systems
Importance: Medium
Assignee: bugproxy (bugproxy)
Status: New
** Affects: llvm-toolchain-18 (Ubuntu)
Importance: Medium
Status: New
** Tags: reverse-proxy-bugzilla s390x
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https://bugs.launchpad.net/bugs/2075491
Title:
binary16 float-point arithmetic crashes LLVM on s390x
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