Remove some x86-64 addressing modes of IMUL and ADD instructions

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1

Hello everyone,

For some project, I need to remove some addressing modes of operands in IMUL and ADD instructions. More specifically, I do not want LLVM to generate instruction like:

imull (%r9,%r11), %r15d

Instead I will like LLVM to generate code which first loads address into a register and then multiply it, i.e., something like:

movl (%r9, %r11), %r10d
imull %r10d, %r15d

I have remove all IMUL64rm and IMUL64rmi instructions in Target/X86/X86InstrArithmetic.td, but still imull instruction with memory operand is generated. Can anyone please point me to the write place?

I will prefer a solution related to llvm6.0, however, solution for any llvm version is welcome.

Thank You,

Abhinav Jangda

2

Did you also remove IMUL32rm and IMUL32rmi? The example assembly you provides look to be 32-bit multiplies since they use %r15d and %r10d.