diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/nativeGen/X86/Regs.hs | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/compiler/nativeGen/X86/Regs.hs b/compiler/nativeGen/X86/Regs.hs index 6af9bc9c15..b2b6a3413a 100644 --- a/compiler/nativeGen/X86/Regs.hs +++ b/compiler/nativeGen/X86/Regs.hs @@ -471,6 +471,11 @@ callClobberedRegs :: [Reg] freeReg esp = fastBool False -- %esp is the C stack pointer #endif +#if i386_TARGET_ARCH +freeReg esi = fastBool False -- Note [esi/edi not allocatable] +freeReg edi = fastBool False +#endif + #if x86_64_TARGET_ARCH freeReg rsp = fastBool False -- %rsp is the C stack pointer #endif @@ -662,4 +667,16 @@ allocatableRegs = let isFree i = isFastTrue (freeReg i) in map RealRegSingle $ filter isFree allMachRegNos +{- +Note [esi/edi not allocatable] + +%esi is mapped to R1, so %esi would normally be allocatable while it +is not being used for R1. However, %esi has no 8-bit version on x86, +and the linear register allocator is not sophisticated enough to +handle this irregularity (we need more RegClasses). The +graph-colouring allocator also cannot handle this - it was designed +with more flexibility in mind, but the current implementation is +restricted to the same set of classes as the linear allocator. +Hence, on x86 esi and edi are treated as not allocatable. +-} |