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float t1(int argc) { return (argc == 1123) ? 1.234f : 2.38213f; } We would generate truly awful code on ARM (those with a weak stomach should look away): _t1: movw r1, #1123 movs r2, #1 movs r3, #0 cmp r0, r1 mov.w r0, #0 it eq moveq r0, r2 movs r1, #4 cmp r0, #0 it ne movne r3, r1 adr r0, #LCPI1_0 ldr r0, [r0, r3] bx lr The problem was that legalization was creating a cascade of SELECT_CC nodes, for for the comparison of "argc == 1123" which was fed into a SELECT node for the ?: statement which was itself converted to a SELECT_CC node. This is because the ARM back-end doesn't have custom lowering for SELECT nodes, so it used the default "Expand". I added a fairly simple "LowerSELECT" to the ARM back-end. It takes care of this testcase, but can obviously be expanded to include more cases. Now we generate this, which looks optimal to me: _t1: movw r1, #1123 movs r2, #0 cmp r0, r1 adr r0, #LCPI0_0 it eq moveq r2, #4 ldr r0, [r0, r2] bx lr .align 2 LCPI0_0: .long 1075344593 @ float 2.382130e+00 .long 1067316150 @ float 1.234000e+00 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110799 91177308-0d34-0410-b5e6-96231b3b80d8 |
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Analysis | ||
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Assembler | ||
Bindings/Ocaml | ||
Bitcode | ||
BugPoint | ||
CodeGen | ||
DebugInfo | ||
ExecutionEngine | ||
Feature | ||
FrontendAda | ||
FrontendC | ||
FrontendC++ | ||
FrontendFortran | ||
FrontendObjC | ||
FrontendObjC++ | ||
Integer | ||
lib | ||
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LLVMC | ||
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CMakeLists.txt | ||
lit.cfg | ||
lit.site.cfg.in | ||
Makefile | ||
Makefile.tests | ||
site.exp.in | ||
TestRunner.sh |