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authorJoseph Myers <joseph@codesourcery.com>2015-02-06 15:44:07 +0000
committerJoseph Myers <joseph@codesourcery.com>2015-02-06 15:44:07 +0000
commit1c7a4a51a30dd001c81630156458ee55fc2e883c (patch)
tree3116ff19257a9cb385bc0f70d67becdb742d0395 /soft-fp
parent61f006c12d8ff3a80a95a36fed81c908a2e39650 (diff)
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soft-fp: Fix _FP_FMA when product is zero and third argument is finite (bug 17932).
soft-fp's _FP_FMA fails to set the result's exponent for cases where the result of the multiplication is 0, yielding incorrect (arbitrary, depending on uninitialized values) results for those cases. This affects libm for architectures using soft-fp to implement fma. This patch adds the exponent setting and tests for this case. Tested for ARM soft-float (which uses soft-fp fma), x86_64 and x86 (to verify not introducing new libm test failures there). (This bug showed up in testing my patch to move the Linux kernel to current soft-fp. math/Makefile has "override CFLAGS += -Wno-uninitialized" which would have stopped compiler warnings from showing up this problem, although I wouldn't be surprised if removing that shows spurious warnings from this code, if the compiler fails to follow that various cases where the exponent is uninitialized don't need it initialized because the class is set to a value meaning the uninitialized exponent isn't used.) [BZ #17932] * soft-fp/op-common.h (_FP_FMA): Set exponent of result in case where multiplication results in zero and third argument is finite and nonzero. * math/auto-libm-test-in: Add more tests of fma. * math/auto-libm-test-out: Regenerated.
Diffstat (limited to 'soft-fp')
-rw-r--r--soft-fp/op-common.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/soft-fp/op-common.h b/soft-fp/op-common.h
index 389ba3f..342532a 100644
--- a/soft-fp/op-common.h
+++ b/soft-fp/op-common.h
@@ -1116,6 +1116,7 @@
R##_s = Z##_s; \
_FP_FRAC_COPY_##wc (R, Z); \
R##_c = Z##_c; \
+ R##_e = Z##_e; \
break; \
\
case _FP_CLS_COMBINE (FP_CLS_INF, FP_CLS_INF): \