https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58623
--- Comment #4 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> --- (In reply to bin.cheng from comment #3) > Patch sent at https://gcc.gnu.org/ml/gcc-patches/2014-11/msg02209.html > On latest trunk, the patch generates below assembly for the example: > > .cpu generic+fp+simd > .file "pr58623.c" > .text > .align 2 > .global foo > .type foo, %function > foo: > adrp x0, .LANCHOR0 > add x2, x0, :lo12:.LANCHOR0 > ldr x1, [x0, #:lo12:.LANCHOR0] > ldr x0, [x2, 8] > add w0, w1, w0 > ret > .size foo, .-foo > .align 2 > .global bar > .type bar, %function > bar: > adrp x1, .LANCHOR0 > add x1, x1, :lo12:.LANCHOR0 > ldp w2, w0, [x1, 16] > add w0, w2, w0 > ret > .size bar, .-bar > .global d > .global c > .global b > .global a > .bss > .align 3 > .LANCHOR0 = . + 0 > .type a, %object > .size a, 8 > a: > .zero 8 > .type b, %object > .size b, 8 > b: > .zero 8 > .type c, %object > .size c, 4 > c: > .zero 4 > .type d, %object > .size d, 4 > d: > .zero 4 > .ident "GCC: (GNU) 5.0.0 20141118 (experimental)" > > ldp opportunity in bar is captured, but not the one in foo. Apparently, > fwprop pass propagates the expression into memory reference, corrupting the > pair opportunity. This is another known issue for long time. So I think we should take the fwprop issue as a separate bug and close this out for 5.0 as the main work required to generate ldp / stp in the compiler is now done.
