x86 compiler should handle the "div/rem by 1" case
The current implementation of the (div/rem)/imm algorithm in
ART's x86 compiler (X86Mir2Lir::GenDivRemLit) handles the only
case when imm == -1, imm >= 2 and imm <= -2, but in the case
when imm == 1, the result of calculation is incorrect.
This patch adds handler of the "div/rem by 1" case.
Change-Id: I4bcdcd9c17f5ccb6c60e7c359c00e04cd07f5bee
Signed-off-by: Alexei Zavjalov <alexei.zavjalov@intel.com>
diff --git a/compiler/dex/quick/x86/int_x86.cc b/compiler/dex/quick/x86/int_x86.cc
index 9dd6116..1df9254 100644
--- a/compiler/dex/quick/x86/int_x86.cc
+++ b/compiler/dex/quick/x86/int_x86.cc
@@ -456,10 +456,20 @@
RegLocation rl_result = {kLocPhysReg, 0, 0, 0, 0, 0, 0, 0, 1, kVectorNotUsed,
r2, INVALID_REG, INVALID_SREG, INVALID_SREG};
- // handle 0x80000000 / -1 special case.
- LIR *minint_branch = 0;
- if (imm == -1) {
+ // handle div/rem by 1 special case.
+ if (imm == 1) {
if (is_div) {
+ // x / 1 == x.
+ StoreValue(rl_result, rl_src);
+ } else {
+ // x % 1 == 0.
+ LoadConstantNoClobber(r0, 0);
+ // For this case, return the result in EAX.
+ rl_result.low_reg = r0;
+ }
+ } else if (imm == -1) { // handle 0x80000000 / -1 special case.
+ if (is_div) {
+ LIR *minint_branch = 0;
LoadValueDirectFixed(rl_src, r0);
OpRegImm(kOpCmp, r0, 0x80000000);
minint_branch = NewLIR2(kX86Jcc8, 0, kX86CondEq);
@@ -479,7 +489,7 @@
// For this case, return the result in EAX.
rl_result.low_reg = r0;
} else {
- DCHECK(imm <= -2 || imm >= 2);
+ CHECK(imm <= -2 || imm >= 2);
// Use H.S.Warren's Hacker's Delight Chapter 10 and
// T,Grablund, P.L.Montogomery's Division by invariant integers using multiplication.
int magic, shift;