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llvm-project/llvm/test/CodeGen/X86/2008-04-26-Asm-Optimize-Imm.ll

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Implement a signficant optimization for inline asm: When choosing between constraints with multiple options, like "ir", test to see if we can use the 'i' constraint and go with that if possible. This produces more optimal ASM in all cases (sparing a register and an instruction to load it), and fixes inline asm like this: void test () { asm volatile (" %c0 %1 " : : "imr" (42), "imr"(14)); } Previously we would dump "42" into a memory location (which is ok for the 'm' constraint) which would cause a problem because the 'c' modifier is not valid on memory operands. Isn't it great how inline asm turns 'missed optimization' into 'compile failed'?? Incidentally, this was the todo in PowerPC/2007-04-24-InlineAsm-I-Modifier.ll Please do NOT pull this into Tak. llvm-svn: 50315
2008-04-27 08:37:18 +08:00
; RUN: llvm-as < %s | llc | grep {1 \$2 3}
; rdar://5720231
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin8"
define void @test() nounwind {
entry:
tail call void asm sideeffect " ${0:c} $1 ${2:c} ", "imr,imr,i,~{dirflag},~{fpsr},~{flags}"( i32 1, i32 2, i32 3 ) nounwind
ret void
}