Add different "cast constant value" for several possible types.

Note these are actually generated by Phis with constant operands.

llvm-svn: 685
This commit is contained in:
Vikram S. Adve 2001-10-01 00:23:12 +00:00
parent fd72440286
commit 35622c3fc0
1 changed files with 19 additions and 10 deletions

View File

@ -15,17 +15,24 @@ begin
end end
; A constant argument to a Phi produces a Cast instruction in the ; A constant argument to a Phi produces a Cast instruction in the
; corresponding predecessor basic block. This has little to do with ; corresponding predecessor basic block. This checks a few things:
; selection but the code is a bit weird. ; -- phi arguments coming from the bottom of the same basic block
; (they should not be forward substituted in the machine code!)
; -- code generation for casts of various types
; -- use of immediate fields for integral constants of different sizes
; -- branch on a constant condition
; ;
void "mergeConstants"(int * %x, int * %y) void "mergeConstants"(int * %x, int * %y)
begin begin
; <label>:0 ; [#uses=1] ; <label>:0
br label %Top br label %Top
Top: ; [#uses=4] Top:
phi int [ 0, %0 ], [ 1, %Top ], [ 2, %Next ] ; <int>:0 [#uses=0] phi int [ 0, %0 ], [ 1, %Top ], [ 524288, %Next ]
phi float [ 0.0, %0 ], [ 1.0, %Top ], [ 2.0, %Next ]
phi double [ 0.5, %0 ], [ 1.5, %Top ], [ 2.5, %Next ]
phi bool [ true, %0 ], [ false,%Top ], [ true, %Next ]
br bool true, label %Top, label %Next br bool true, label %Top, label %Next
Next: ; [#uses=2] Next:
br label %Top br label %Top
end end
@ -71,10 +78,12 @@ end
; Test cases where an LLVM instruction requires no machine ; Test cases where an LLVM instruction requires no machine
; instructions (e.g., cast int* to long). But there are 2 cases: ; instructions (e.g., cast int* to long). But there are 2 cases:
; 1. If the result register has only a single use, the operand will be ; 1. If the result register has only a single use and the use is in the
; copy-propagated during instruction selection. ; same basic block, the operand will be copy-propagated during
; 2. If the result register has multiple uses, it cannot be copy ; instruction selection.
; propagated during instruction selection. It will generate a ; 2. If the result register has multiple uses or is in a different
; basic block, it cannot (or will not) be copy propagated during
; instruction selection. It will generate a
; copy instruction (add-with-0), but this copy should get coalesced ; copy instruction (add-with-0), but this copy should get coalesced
; away by the register allocator. ; away by the register allocator.
; ;