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Diffstat (limited to 'lib/Target/PowerPC/README.txt')
| -rw-r--r-- | lib/Target/PowerPC/README.txt | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/lib/Target/PowerPC/README.txt b/lib/Target/PowerPC/README.txt index 8f265cf..3465779 100644 --- a/lib/Target/PowerPC/README.txt +++ b/lib/Target/PowerPC/README.txt @@ -889,9 +889,26 @@ entry: ; recognize a more elaborate tree than a simple SETxx. define double @test_FNEG_sel(double %A, double %B, double %C) { - %D = sub double -0.000000e+00, %A ; <double> [#uses=1] + %D = fsub double -0.000000e+00, %A ; <double> [#uses=1] %Cond = fcmp ugt double %D, -0.000000e+00 ; <i1> [#uses=1] %E = select i1 %Cond, double %B, double %C ; <double> [#uses=1] ret double %E } +//===----------------------------------------------------------------------===// +The save/restore sequence for CR in prolog/epilog is terrible: +- Each CR subreg is saved individually, rather than doing one save as a unit. +- On Darwin, the save is done after the decrement of SP, which means the offset +from SP of the save slot can be too big for a store instruction, which means we +need an additional register (currently hacked in 96015+96020; the solution there +is correct, but poor). +- On SVR4 the same thing can happen, and I don't think saving before the SP +decrement is safe on that target, as there is no red zone. This is currently +broken AFAIK, although it's not a target I can exercise. +The following demonstrates the problem: +extern void bar(char *p); +void foo() { + char x[100000]; + bar(x); + __asm__("" ::: "cr2"); +} |