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to Brian and the Sun compiler for pointing out that the obvious works :) This also enables folding all long comparisons into setcc and branch instructions: before we could only do == and != For example, for: void test(unsigned long long A, unsigned long long B) { if (A < B) foo(); } We now generate: test: subl $4, %esp movl %esi, (%esp) movl 8(%esp), %eax movl 12(%esp), %ecx movl 16(%esp), %edx movl 20(%esp), %esi subl %edx, %eax sbbl %esi, %ecx jae .LBBtest_2 # UnifiedReturnBlock .LBBtest_1: # then call foo movl (%esp), %esi addl $4, %esp ret .LBBtest_2: # UnifiedReturnBlock movl (%esp), %esi addl $4, %esp ret Instead of: test: subl $12, %esp movl %esi, 8(%esp) movl %ebx, 4(%esp) movl 16(%esp), %eax movl 20(%esp), %ecx movl 24(%esp), %edx movl 28(%esp), %esi cmpl %edx, %eax setb %al cmpl %esi, %ecx setb %bl cmove %ax, %bx testb %bl, %bl je .LBBtest_2 # UnifiedReturnBlock .LBBtest_1: # then call foo movl 4(%esp), %ebx movl 8(%esp), %esi addl $12, %esp ret .LBBtest_2: # UnifiedReturnBlock movl 4(%esp), %ebx movl 8(%esp), %esi addl $12, %esp ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18330 91177308-0d34-0410-b5e6-96231b3b80d8 |
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.. | ||
.cvsignore | ||
Makefile | ||
X86.h | ||
X86.td | ||
X86AsmPrinter.cpp | ||
X86CodeEmitter.cpp | ||
X86FloatingPoint.cpp | ||
X86InstrBuilder.h | ||
X86InstrInfo.cpp | ||
X86InstrInfo.h | ||
X86InstrInfo.td | ||
X86ISelPattern.cpp | ||
X86ISelSimple.cpp | ||
X86JITInfo.cpp | ||
X86JITInfo.h | ||
X86PeepholeOpt.cpp | ||
X86RegisterInfo.cpp | ||
X86RegisterInfo.h | ||
X86RegisterInfo.td | ||
X86Relocations.h | ||
X86TargetMachine.cpp | ||
X86TargetMachine.h |