[SPIR-V] `-Gis` flag causing invalid SPIR-V to be generated for `mad` for 32 bit integers

https://godbolt.org/z/1q18evbx7

Compiling this code with the -Gis flag enabled

// RUN: %dxc -spirv -fspv-target-env=vulkan1.3 -Gis -HV 202x -T cs_6_5 %s

StructuredBuffer<int4> M1 : register(t3);
StructuredBuffer<int4> A1 : register(t4);
StructuredBuffer<int4> B1 : register(t5);
RWStructuredBuffer<int4> Out1 : register(u10);

[numthreads(1,1,1)]
void main() {
  Out1[0] = mad(M1[0], A1[0], B1[0]);
}

is producing this error:

# .---command stderr------------
# | fatal error: generated SPIR-V is invalid: ID '30' decorated with NoContraction multiple times is not allowed.
# |   %30 = OpIMul %v4int %152 %154
# | 
# `-----------------------------
# error: command failed with exit status: 0x80004005

The same error occurs when using uint as well.

-Gis should only impact floating point operations, so there's likely a bug in DXC causing it to add floating point flags to an integer operation.