mirror of
https://github.com/c64scene-ar/llvm-6502.git
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9bf654646e
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@621 91177308-0d34-0410-b5e6-96231b3b80d8
94 lines
2.7 KiB
LLVM
94 lines
2.7 KiB
LLVM
implementation
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; A SetCC whose result is used should produce instructions to
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; compute the boolean value in a register. One whose result
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; is unused will only generate the condition code but not
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; the boolean result.
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;
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void "unusedBool"(int * %x, int * %y)
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begin
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; <label>:0 ; [#uses=0]
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seteq int * %x, %y ; <bool>:0 [#uses=1]
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not bool %0 ; <bool>:1 [#uses=0]
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setne int * %x, %y ; <bool>:2 [#uses=0]
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ret void
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end
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; A constant argument to a Phi produces a Cast instruction in the
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; corresponding predecessor basic block. This has little to do with
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; selection but the code is a bit weird.
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;
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void "mergeConstants"(int * %x, int * %y)
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begin
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; <label>:0 ; [#uses=1]
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br label %Top
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Top: ; [#uses=4]
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phi int [ 0, %0 ], [ 1, %Top ], [ 2, %Next ] ; <int>:0 [#uses=0]
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br bool true, label %Top, label %Next
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Next: ; [#uses=2]
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br label %Top
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end
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; Test branch-on-comparison-with-zero, in two ways:
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; 1. can be folded
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; 2. cannot be folded because result of comparison is used twice
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;
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void "testbool"(int, int) ; Def %0, %1
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int 0 ; Def 2
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int -4 ; Def 3
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begin
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add int %0, %1 ; Def 4
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sub int %4, %3 ; Def 5
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setle int %5, %2 ; Def 0 - bool plane
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br bool %0, label %retlbl, label %loop
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loop:
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add int %0, %1 ; Def 6
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sub int %4, %3 ; Def 7
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setle int %7, %2 ; Def 1 - bool
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not bool %1 ; Def 2 - bool. first use of bool %1
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br bool %1, label %loop, label %0 ; second use of bool %1
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retlbl:
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ret void
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end
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; Test branch on floating point comparison
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;
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void "testfloatbool"(float %x, float %y) ; Def %0, %1 - float
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begin
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%p = add float %x, %y ; Def 2 - float
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%z = sub float %x, %y ; Def 3 - float
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%b = setle float %p, %z ; Def 0 - bool
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%c = not bool %b ; Def 1 - bool
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br bool %b, label %0, label %goon
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goon:
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ret void
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end
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; Test cases where an LLVM instruction requires no machine
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; instructions (e.g., cast int* to long). But there are 2 cases:
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; 1. If the result register has only a single use, the operand will be
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; copy-propagated during instruction selection.
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; 2. If the result register has multiple uses, it cannot be copy
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; propagated during instruction selection. It will generate a
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; copy instruction (add-with-0), but this copy should get coalesced
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; away by the register allocator.
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;
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int "checkForward"(int %N, int* %A)
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begin
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bb2: ;;<label>
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%reg114 = shl int %N, ubyte 2 ;;
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%cast115 = cast int %reg114 to int* ;; reg114 will be propagated
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%reg116 = add int* %A, %cast115 ;;
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%reg118 = load int* %reg116 ;;
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%cast117 = cast int %reg118 to long ;; reg118 will be copied 'cos
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%reg159 = add long 1234567, %cast117 ;; cast117 has 2 uses, here
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%reg160 = add long 7654321, %cast117 ;; and here.
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ret void
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end
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