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b409a61574
uint32_t hi(uint64_t res)
{
uint_32t hi = res >> 32;
return !hi;
}
llvm IR looks like this:
define i32 @hi(i64 %res) nounwind uwtable ssp {
entry:
%lnot = icmp ult i64 %res, 4294967296
%lnot.ext = zext i1 %lnot to i32
ret i32 %lnot.ext
}
The optimizer has optimize away the right shift and truncate but the resulting
constant is too large to fit in the 32-bit immediate field. The resulting x86
code is worse as a result:
movabsq $4294967296, %rax ## imm = 0x100000000
cmpq %rax, %rdi
sbbl %eax, %eax
andl $1, %eax
This patch teaches the x86 lowering code to handle ult against a large immediate
with trailing zeros. It will issue a right shift and a truncate followed by
a comparison against a shifted immediate.
shrq $32, %rdi
testl %edi, %edi
sete %al
movzbl %al, %eax
It also handles a ugt comparison against a large immediate with trailing bits
set. i.e. X > 0x0ffffffff -> (X >> 32) >= 1
rdar://11866926
llvm-svn: 160312
66 lines
3.2 KiB
LLVM
66 lines
3.2 KiB
LLVM
; RUN: llc < %s -mtriple=x86_64-apple-darwin -mcpu=core2 | FileCheck %s
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; Reduced from JavaScriptCore
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%"class.JSC::CodeLocationCall" = type { [8 x i8] }
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%"class.JSC::JSGlobalData" = type { [4 x i8] }
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%"class.JSC::FunctionPtr" = type { i8* }
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%"class.JSC::Structure" = type { [4 x i8] }
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%"class.JSC::UString" = type { i8* }
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%"class.JSC::JSString" = type { [16 x i8], i32, %"class.JSC::UString", i32 }
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declare hidden fastcc void @_ZN3JSCL23returnToThrowTrampolineEPNS_12JSGlobalDataENS_16ReturnAddressPtrERS2_(%"class.JSC::JSGlobalData"* nocapture, i8*, %"class.JSC::FunctionPtr"* nocapture) nounwind noinline ssp
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; Avoid hoisting the test above loads or copies
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; CHECK: %entry
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; CHECK: test
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; CHECK-NOT: mov
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; CHECK: je
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define i32 @cti_op_eq(i8** nocapture %args) nounwind ssp {
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entry:
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%0 = load i8** null, align 8
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%tmp13 = bitcast i8* %0 to %"class.JSC::CodeLocationCall"*
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%tobool.i.i.i = icmp ugt i8* undef, inttoptr (i64 281474976710655 to i8*)
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%or.cond.i = and i1 %tobool.i.i.i, undef
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br i1 %or.cond.i, label %if.then.i, label %if.end.i
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if.then.i: ; preds = %entry
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br i1 undef, label %if.then.i.i.i, label %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
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if.then.i.i.i: ; preds = %if.then.i
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%conv.i.i.i.i = trunc i64 undef to i32
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br label %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
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if.end.i: ; preds = %entry
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br i1 undef, label %land.rhs.i121.i, label %_ZNK3JSC7JSValue8isStringEv.exit122.i
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land.rhs.i121.i: ; preds = %if.end.i
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%tmp.i.i117.i = load %"class.JSC::Structure"** undef, align 8
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br label %_ZNK3JSC7JSValue8isStringEv.exit122.i
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_ZNK3JSC7JSValue8isStringEv.exit122.i: ; preds = %land.rhs.i121.i, %if.end.i
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%brmerge.i = or i1 undef, false
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%or.cond = or i1 false, %brmerge.i
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br i1 %or.cond, label %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit, label %if.then.i92.i
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if.then.i92.i: ; preds = %_ZNK3JSC7JSValue8isStringEv.exit122.i
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tail call void @_ZNK3JSC8JSString11resolveRopeEPNS_9ExecStateE(%"class.JSC::JSString"* undef, %"class.JSC::CodeLocationCall"* %tmp13) nounwind
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unreachable
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_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit: ; preds = %_ZNK3JSC7JSValue8isStringEv.exit122.i, %if.then.i.i.i, %if.then.i
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%1 = load i8** undef, align 8
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br i1 undef, label %do.end39, label %do.body27
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do.body27: ; preds = %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
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%tmp30 = bitcast i8* %1 to %"class.JSC::JSGlobalData"*
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%2 = getelementptr inbounds i8** %args, i64 -1
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%3 = bitcast i8** %2 to %"class.JSC::FunctionPtr"*
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tail call fastcc void @_ZN3JSCL23returnToThrowTrampolineEPNS_12JSGlobalDataENS_16ReturnAddressPtrERS2_(%"class.JSC::JSGlobalData"* %tmp30, i8* undef, %"class.JSC::FunctionPtr"* %3)
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unreachable
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do.end39: ; preds = %_ZN3JSC7JSValue19equalSlowCaseInlineEPNS_9ExecStateES0_S0_.exit
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ret i32 undef
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}
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declare void @_ZNK3JSC8JSString11resolveRopeEPNS_9ExecStateE(%"class.JSC::JSString"*, %"class.JSC::CodeLocationCall"*)
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