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authorIan Romanick <[email protected]>2020-03-04 12:23:13 -0800
committerMarge Bot <[email protected]>2020-03-18 20:36:29 +0000
commitda3fa01891ec41ced3cbe2b63e8e5c8252e6e7ba (patch)
tree37bfa18eb6c6c84cebf189205248f50ea60881b5 /src/compiler
parent3c9ff97215b0c13c82f460dcc59cb61f6b02d78c (diff)
soft-fp64/fadd: Rename aFrac and bFrac variables
Exchanging aFracHi / bFracHi and aFracLo / bFracLo should not affect the result of the later call to __add64. The main purpose of this commit is to prepare for "soft-fp64/fadd: Move common code out of both branches of an if-statement". v2: Fix a typo in a comment. Noticed by Matt. Results on the 308 shaders extracted from the fp64 portion of the OpenGL CTS: Tiger Lake and Ice Lake had similar results. (Tiger Lake shown) total instructions in shared programs: 812094 -> 818246 (0.76%) instructions in affected programs: 750271 -> 756423 (0.82%) helped: 0 HURT: 74 HURT stats (abs) min: 7 max: 520 x̄: 83.14 x̃: 59 HURT stats (rel) min: 0.52% max: 1.48% x̄: 0.89% x̃: 0.84% 95% mean confidence interval for instructions value: 63.96 102.31 95% mean confidence interval for instructions %-change: 0.83% 0.95% Instructions are HURT. total cycles in shared programs: 6797157 -> 6816686 (0.29%) cycles in affected programs: 6365175 -> 6384704 (0.31%) helped: 0 HURT: 74 HURT stats (abs) min: 16 max: 1690 x̄: 263.91 x̃: 181 HURT stats (rel) min: 0.14% max: 0.68% x̄: 0.32% x̃: 0.27% 95% mean confidence interval for cycles value: 199.74 328.07 95% mean confidence interval for cycles %-change: 0.29% 0.36% Cycles are HURT. total spills in shared programs: 703 -> 705 (0.28%) spills in affected programs: 703 -> 705 (0.28%) helped: 0 HURT: 1 total fills in shared programs: 1499 -> 1501 (0.13%) fills in affected programs: 1499 -> 1501 (0.13%) helped: 0 HURT: 1 Reviewed-by: Matt Turner <[email protected]> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4142>
Diffstat (limited to 'src/compiler')
-rw-r--r--src/compiler/glsl/float64.glsl27
1 files changed, 21 insertions, 6 deletions
diff --git a/src/compiler/glsl/float64.glsl b/src/compiler/glsl/float64.glsl
index 40cc84439fb..cdecfdb8dbb 100644
--- a/src/compiler/glsl/float64.glsl
+++ b/src/compiler/glsl/float64.glsl
@@ -661,6 +661,17 @@ __propagateFloat64NaN(uint64_t __a, uint64_t __b)
#endif
}
+/* If a shader is in the soft-fp64 path, it almost certainly has register
+ * pressure problems. Choose a method to exchange two values that does not
+ * require a temporary.
+ */
+#define EXCHANGE(a, b) \
+ do { \
+ a ^= b; \
+ b ^= a; \
+ a ^= b; \
+ } while (false)
+
/* Returns the result of adding the double-precision floating-point values
* `a' and `b'. The operation is performed according to the IEEE Standard for
* Floating-Point Arithmetic.
@@ -709,15 +720,19 @@ __fadd64(uint64_t a, uint64_t b)
bFracHi, bFracLo, 0u, expDiff, bFracHi, bFracLo, zFrac2);
zExp = aExp;
} else {
- if (bExp == 0x7FF) {
- bool propagate = (bFracHi | bFracLo) != 0u;
+ EXCHANGE(aFracHi, bFracHi);
+ EXCHANGE(aFracLo, bFracLo);
+ EXCHANGE(aExp, bExp);
+
+ if (aExp == 0x7FF) {
+ bool propagate = (aFracHi | aFracLo) != 0u;
return mix(__packFloat64(aSign, 0x7ff, 0u, 0u), __propagateFloat64NaN(a, b), propagate);
}
- expDiff = mix(expDiff, expDiff + 1, aExp == 0);
- aFracHi = mix(aFracHi | 0x00100000u, aFracHi, aExp == 0);
+ expDiff = mix(expDiff, expDiff + 1, bExp == 0);
+ bFracHi = mix(bFracHi | 0x00100000u, bFracHi, bExp == 0);
__shift64ExtraRightJamming(
- aFracHi, aFracLo, 0u, - expDiff, aFracHi, aFracLo, zFrac2);
- zExp = bExp;
+ bFracHi, bFracLo, 0u, - expDiff, bFracHi, bFracLo, zFrac2);
+ zExp = aExp;
}
aFracHi |= 0x00100000u;